There are 50 goats, 3 more than 4/5 goats. How many sheep are there?
3. Read a book with 120 pages. You read the whole book 1/3. How many pages are exactly 5/6 of the whole book?
4. A bottle of oil is 4/5 Jin, and 3/ 10 Jin has been used. 1/2 how many kilograms of oil does it take?
5. A bag of rice 120kg. On the first day, you eat 1/4, and on the second day, you eat the rest 1/3. How many Jin did you eat the next day?
6. For a batch of goods, one car can transport 1/8 at a time, and how many parts can be transported four times? If this shipment weighs 1 16 tons, how many tons have been shipped?
7. A factory used 28 tons of water in September,1planned saving in October 1/7. /kloc-How many tons do you plan to save in October?
8. The base of parallelogram is 24 meters long and its height is 3/4 of the base. What is its area?
9. Human blood accounts for113 of body weight, about two-thirds of blood is water, and dad's weight is 78kg. How many kilograms is his blood?
10, Grade 6 students participated in tree planting, boys planted 160 trees, and girls planted 5 more trees than 3/4 boys. How many trees do girls plant?
1 1. The number of students in the fourth grade of Guangxin Primary School is 4/5 of that in the fifth grade, and that in the third grade is 2/3 of that in the fourth grade. If the number of students in grade five is 120, how many are there in grade three?
12, two cars A and B leave from A and B at the same time, with a distance of 420km. After 5 hours, A walked 3/4 of the whole journey and B walked 2/3 of the whole journey. How many kilometers are the two cars apart?
13, 120 trees were planted in grade five, and the number of trees planted in grade six was 7/5 of that in grade five. How many trees were planted in the fifth and sixth grades?
14. A road of 12/5km was built. 2/3km was built in the first week and 1/3 was built in the second week. How many kilometers were built in two weeks?
15. A highway is 7/8 kilometers long. 1/8km was built on the first day. How many kilometers will the total length of 1/2 be more?
16, Xiaohua read a 96-page story book. The first day he read 1/4, and the next day he read 1/8. How many pages have you read in two days?
17. A book has 150 pages. On the first day, Xiao Wang read110, and on the second day, he read115. Which page should he start from on the third day?
18, the school transported 2/5 tons of cement, and the yellow sand transported was 5/8 of the cement, which was 1/8 tons more. How many tons of yellow sand were shipped?
19, Xiao Wei and Xiaoying contributed 2:5 to Project Hope. Xiaoying donated 35 yuan. How much did Xiao Wei donate?
The TV factory plans to increase its output by two-fifths this year compared with last year. Last year,1/50,000 TV sets were produced. Tens of thousands of TV sets are planned to be added this year? 1, a rope is 4/5 meters long. First,1/4m is needed, and then1/4m is needed. How many meters does a * * * need?
There are 50 goats, 3 more than 4/5 goats. How many sheep are there?
3. Read a book with 120 pages. You read the whole book 1/3. How many pages are exactly 5/6 of the whole book?
4. A bottle of oil is 4/5 Jin, and 3/ 10 Jin has been used. 1/2 how many kilograms of oil does it take?
5. A bag of rice 120kg. On the first day, you eat 1/4, and on the second day, you eat the rest 1/3. How many Jin did you eat the next day?
6. For a batch of goods, one car can transport 1/8 at a time, and how many parts can be transported four times? If this shipment weighs 1 16 tons, how many tons have been shipped?
7. A factory used 28 tons of water in September,1planned saving in October 1/7. /kloc-How many tons do you plan to save in October?
8. The base of parallelogram is 24 meters long and its height is 3/4 of the base. What is its area?
9. Human blood accounts for113 of body weight, about two-thirds of blood is water, and dad's weight is 78kg. How many kilograms is his blood?
10, Grade 6 students participated in tree planting, boys planted 160 trees, and girls planted 5 more trees than 3/4 boys. How many trees do girls plant?
1 1. The number of students in the fourth grade of Guangxin Primary School is 4/5 of that in the fifth grade, and that in the third grade is 2/3 of that in the fourth grade. If the number of students in grade five is 120, how many are there in grade three?
12, two cars A and B leave from A and B at the same time, with a distance of 420km. After 5 hours, A walked 3/4 of the whole journey and B walked 2/3 of the whole journey. How many kilometers are the two cars apart?
13, 120 trees were planted in grade five, and the number of trees planted in grade six was 7/5 of that in grade five. How many trees were planted in the fifth and sixth grades?
14. A road of 12/5km was built. 2/3km was built in the first week and 1/3 was built in the second week. How many kilometers were built in two weeks?
15. A highway is 7/8 kilometers long. 1/8km was built on the first day. How many kilometers will the total length of 1/2 be more?
16, Xiaohua read a 96-page story book. The first day he read 1/4, and the next day he read 1/8. How many pages have you read in two days?
17. A book has 150 pages. On the first day, Xiao Wang read110, and on the second day, he read115. Which page should he start from on the third day?
18, the school transported 2/5 tons of cement, and the yellow sand transported was 5/8 of the cement, which was 1/8 tons more. How many tons of yellow sand were shipped?
19, Xiao Wei and Xiaoying contributed 2:5 to Project Hope. Xiaoying donated 35 yuan. How much did Xiao Wei donate?
The TV factory plans to increase its output by two-fifths this year compared with last year. Last year,1/50,000 TV sets were produced. Tens of thousands of TV sets are planned to be added this year? 1, a rope is 4/5 meters long. First,1/4m is needed, and then1/4m is needed. How many meters does a * * * need?
There are 50 goats, 3 more than 4/5 goats. How many sheep are there?
3. Read a book with 120 pages. You read the whole book 1/3. How many pages are exactly 5/6 of the whole book?
4. A bottle of oil is 4/5 Jin, and 3/ 10 Jin has been used. 1/2 how many kilograms of oil does it take?
5. A bag of rice 120kg. On the first day, you eat 1/4, and on the second day, you eat the rest 1/3. How many Jin did you eat the next day?
6. For a batch of goods, one car can transport 1/8 at a time, and how many parts can be transported four times? If this shipment weighs 1 16 tons, how many tons have been shipped?
7. A factory used 28 tons of water in September,1planned saving in October 1/7. /kloc-How many tons do you plan to save in October?
8. The base of parallelogram is 24 meters long and its height is 3/4 of the base. What is its area?
9. Human blood accounts for113 of body weight, about two-thirds of blood is water, and dad's weight is 78kg. How many kilograms is his blood?
10, Grade 6 students participated in tree planting, boys planted 160 trees, and girls planted 5 more trees than 3/4 boys. How many trees do girls plant?
1 1. The number of students in the fourth grade of Guangxin Primary School is 4/5 of that in the fifth grade, and that in the third grade is 2/3 of that in the fourth grade. If the number of students in grade five is 120, how many are there in grade three?
12, two cars A and B leave from A and B at the same time, with a distance of 420km. After 5 hours, A walked 3/4 of the whole journey and B walked 2/3 of the whole journey. How many kilometers are the two cars apart?
13, 120 trees were planted in grade five, and the number of trees planted in grade six was 7/5 of that in grade five. How many trees were planted in the fifth and sixth grades?
14. A road of 12/5km was built. 2/3km was built in the first week and 1/3 was built in the second week. How many kilometers were built in two weeks?
15. A highway is 7/8 kilometers long. 1/8km was built on the first day. How many kilometers will the total length of 1/2 be more?
16, Xiaohua read a 96-page story book. The first day he read 1/4, and the next day he read 1/8. How many pages have you read in two days?
17. A book has 150 pages. On the first day, Xiao Wang read110, and on the second day, he read115. Which page should he start from on the third day?
18, the school transported 2/5 tons of cement, and the yellow sand transported was 5/8 of the cement, which was 1/8 tons more. How many tons of yellow sand were shipped?
19, Xiao Wei and Xiaoying contributed 2:5 to Project Hope. Xiaoying donated 35 yuan. How much did Xiao Wei donate?
The TV factory plans to increase its output by two-fifths this year compared with last year. Last year,1/50,000 TV sets were produced. Tens of thousands of TV sets are planned to be added this year? 1. To transport 29.5 tons of coal, transport it three times by a truck with a load of 4 tons, and transport the rest by a truck with a load of 2.5 tons. How many times will it take to complete?
It takes x times to complete.
29.5-3 * 4 = 2.5 times
17.5=2.5x
x=7
Seven more shipments are needed to complete.
2. The trapezoidal site covers an area of 90 square meters, with an upper bottom of 7 meters and a lower bottom of 1 1 meter. How high is it?
Its height is x meters.
x(7+ 1 1)=90*2
18x= 180
x= 10
Its height is 10 meter.
A workshop plans to produce 5480 parts in April. It has been in production for 9 days, and 908 more are about to complete the production plan. How many pieces will be produced on average every day in these 9 days?
During these 9 days, X was produced every day on average.
9x+908=5408
9x=4500
x=500
During these nine days, an average of 500 were produced every day.
4. Two cars, Party A and Party B, are driving in opposite directions from two places 272km apart. Three hours later, the distance between the two cars is still 17km. A travels 45 kilometers per hour, and B travels how many kilometers per hour?
B travels x kilometers per hour.
3(45+x)+ 17=272
3(45+x)=255
45+x=85
x=40
B is driving at a speed of 40 kilometers per hour.
5. There are two classes in grade six in a school, and the average score of mathematics last semester is 85. There are 40 students in six classes (1) with an average score of 87. 1. There are 42 students in Class Six (2). What is the average score?
The average score is X.
40*87. 1+42x=85*82
3484+42x=6970
42x=3486
x=83
The average score is 83 points.
6. The school bought 10 boxes of chalk. 250 boxes were used, and there are 550 boxes left. How many boxes per box?
Average x boxes per box
10x=250+550
10x=800
x=80
80 boxes per box on average.
There are 200 students in the fourth grade. During extracurricular activities, 80 girls went to jump rope. The boys are divided into five groups to play football. How many people are in each group?
There are x people in each group on average.
5x+80=200
5x= 160
x=32
There are 32 people in each group on average.
8. The canteen brought 150 kg of rice, which was 30 kg less than the flour. How many kilograms of flour does the canteen send?
The canteen brought x kilograms of flour.
3x-30= 150
3x= 180
x=60
The canteen brought 60 kilograms of flour.
9. There are 52 peach trees and 6 rows of pear trees in the orchard. There are 20 more pear trees than peach trees. How many pear trees are there in each row on average?
There are x pear trees per row on average.
6x-52=20
6x=72
x= 12
There are 12 pear trees in each row on average.
10, the area of a triangle is 840 square meters, the base is 140 meters, and the height is how many meters?
The height is x meters.
140x=840*2
140x= 1680
x= 12
The height is12m.
1 1, Li Shifu bought 72 meters of cloth to make 20 clothes for adults and 16 clothes for children. Adult dresses are 2.4 meters each, and how many meters are children's dresses?
Each piece of children's clothing is made of x meters.
16x+20*2.4=72
16x=72-48
16x=24
x= 1.5
Each piece of children's clothing1.5m.
12, three years ago, my mother was six times older than my daughter. This year, my mother is 33 years old. How old is my daughter?
My daughter is x years old this year.
30=6(x-3)
6x- 18=30
6x=48
x=8
My daughter is 8 years old this year.
13. How long will it take for a car with a speed of 50 kilometers per hour to catch up with a car with a speed of 40 kilometers per hour that left two hours ago?
It takes x time
50x=40x+80
10x=80
x=8
It takes eight hours.
14. Xiaodong bought 3 Jin of apples and 2 Jin of pears at the fruit shop and paid 15 yuan. 1kg apples are more expensive than 1kg pears in 0.5 yuan. How much are apples and pears per kilogram?
Apple x
3x+2(x-0.5)= 15
5x= 16
x=3.2
Apple: 3.2
Pear: 2.7
15, A and B start from A and B at the same time, respectively, in opposite directions. A travels at a speed of 50 kilometers per hour, and B travels at a speed of 40 kilometers per hour. A reaches the midpoint 1 hour earlier than B. How many hours does it take for A to reach the midpoint?
X hours to reach the midpoint.
50x=40(x+ 1)
10x=40
x=4
A reaches the midpoint in 4 hours.
16, Party A and Party B set out from A and B at the same time, face to face, and meet two hours later. If A starts from place A and B goes in the same direction at the same time, then A will catch up with B after 4 hours. Given that the speed of A is 15km/, find the speed of B. ..
Speed x of b
2(x+ 15)+4x=60
2x+30+4x=60
6x=30
x=5
B's speed 5
17. Two ropes with the same length, the first one was cut15m, and the second one was 3m more than the first one. How long are these two ropes?
It turns out that these two ropes are each x meters long.
3(x- 15)+3=x
3x-45+3=x
2x=42
x=2 1
It turns out that the two ropes are each 2 1 m long.
18. A school bought 7 basketballs and 10 soccer balls and paid 248 yuan. As we all know, the price of each basketball is equivalent to the price of three footballs. How much is basketball and football each?
Every basketball x
7x+ 10x/3=248
2 1x+ 10x=744
3 1x=744
x=24
Each basketball: 24
Each football: 8
1, transporting a batch of goods, we have rented these two large trucks twice: for the first time, 2 trucks of Class A and 3 trucks of Class B transported 15.5 tons. The second time, there were 5 vehicles in Class A and 6 vehicles in Class B, and the cargo was transported 35 tons. Now, I rent three Class A cars and five Class B cars from the company. If the freight is paid per ton, 30 yuan asks the owner how much he should pay.
Solution: If A can hold X tons and B can hold Y tons, then
2x+3y= 15.5
5x+6y=35
Get x=4.
y=2.5
Get (3x+5y)*30=735。
2. A commodity is now reduced in price 10% for promotion. In order to keep the total sales amount unchanged, how much is the sales volume increased over the original price?
Solution: Increase X% when selling at the original price.
( 1- 10%)*( 1+X %)= 1
x % = 1 1. 1 1%
In order to keep the total sales amount unchanged, the sales volume increased by11.11%compared with the original price.
3. 10% reduced 1 product price is just over half of the original price. 40 yuan, what is the original price of this product?
Solution: Let the original price be X yuan.
( 1- 10%)x-40=0.5x
x= 100
A: original price 100 yuan.
4. There is 40 grams of salt water with 8% salt. How many grams of salt does it take to make salt water with a salt content of 20%?
Solution: suppose x grams of salt is added.
At first, the pure salt was 40 * 8% g.
Add x grams to make 40 * 8%+X.
Salt water is 40+x grams.
Concentration 20%
So (40*8%+x)/(40+x)=20%.
(3.2+x)/(40+x)=0.2
3.2+x=8+0.2x
0.8x=4.8
x=6
So add 6 grams of salt.
In the market, the sales of eggs are priced according to the quantity. A vendor bought a batch of eggs at a price of 0.24 yuan each, but accidentally broke 12 eggs in the process of selling. The remaining eggs are sold at 0.28 yuan each, and the result is still 1 1.2 yuan's profit. How many eggs did the vendor buy at first?
Solution: Suppose the vendor bought X eggs at first.
List the equations according to the meaning of the question:
(X- 12)* 0.28-0.24 X = 1 1.2
0.28 x-3.36-0.24 x = 1 1.2
0.04X= 14.56
X=364
A: The vendor bought 364 eggs at first.
6. A workshop has 85 technicians. On average, each person can process 15 pieces of A or 10 pieces of B every day, and two pieces of A and three pieces of B are matched with one set. How many people are arranged to process parts A and B respectively to make the two parts processed every day just match?
Solution: Suppose it takes X people to arrange the production of A, then there are (85-x) people to produce B.
Because two A-type parts and three B-type parts are matched with one set, so
Therefore, the number of parts A multiplied by 3 can be equal to the number of parts B multiplied by 2.
16*x*3= 10*(85-x)*2
Solution: x=25
It takes 25 people to produce A and 60 people to produce B!
7. Hong Guang Electric Company can still make a profit of 20% by selling a certain color TV at 20% of the marked price. It is understood that the purchase price of this color TV is 1996 yuan. So what should the price of this color TV be?
Solution: Set the price to X yuan.
80%X= 1996×( 1+20%)
80%X= 2395.2
X=2994
8. A store can make a profit of 20% by selling a commodity at 20% of the marked price. If the purchase price of this commodity is per piece in 22 yuan, what is the list price of each commodity?
Solution: Set the price to X yuan.
80%X=22×( 1+20%)
80%X= 26.4
X=33
9. On a double-track railway, two trains passed head-on. The speed of train A is 20m/s and the speed of train B is 24m/s. If the total length of train A is 180m and the total length of train B is 160m, how many seconds will it take for the two trains to miss each other?
Solution: (180+160)/(20+24) = 7.28 seconds.
10, two students, A and B, walked in the same direction from two places 5 kilometers apart on the same road. Party A's speed is 5km/h, Party B's speed is 3 km/h, and Party A takes the dog. When Party A chases Party B, the dog chases Party B first, then returns to meet Party A, and then returns to chase Party B. It is known that the speed of the dog is 15km/h, and the total distance that the dog runs in this process is calculated.
Solution: First of all, it must be clear that the meeting time between Party A and Party B is equal to the running time of the dog.
So the dog's time = A/B meeting time = the sum of total distance /A/B speed.
=5km/(5km/h+3km/h) = 5/8h
So the distance of the dog = the time of the dog * the speed of the dog =5/8h* 15km/h=75/8km.
So Party A and Party B walked 75/8km, 1. In order to save energy, a unit collects electricity charges according to the following regulations every month: the electricity consumption does not exceed 140 kwh, and it is charged at 0.43 yuan per kwh; If it exceeds 140 degrees, the excess will be charged at 0.57 yuan per degree. If the average electricity bill charged by Mexican consumers in April is 0.5 yuan per kWh, how much should consumers pay in April?
Let the total power consumption be x degrees: [(x-140) * 0.57+140 * 0.43]/x = 0.5.
0.57 times -79.8+60.2 = 0.5 times
0.07x= 19.6
x=280
Step by step: 140*0.43=60.2
(280- 140)*0.57=79.8
79.8+60.2= 140
2. 1) The ratio of delivery staff to sales staff in the home appliance department of a shopping mall is 1: 8. Due to the obvious increase in the purchase of home appliances this summer, the manager of the home appliance department transferred 22 people from the sales staff to deliver the goods. Results The ratio of delivery staff to sales staff was 2: 5. How many delivery staff and sales staff are there in the home appliance department of this shopping mall?
Suppose there are x delivery people and 8X sales people.
(X+22)/(8X-22)=2/5
5*(X+22)=2*(8X-22)
5X+ 1 10 = 16X-44
1 1X= 154
X= 14
8X=8* 14= 1 12
The home appliance department of this shopping mall used to have 14 delivery staff and 1 12 sales staff.
Now a commodity is reduced in price 10% for promotion. In order to keep the sales amount unchanged, how many percent will the sales volume increase over the original price?
Assumption: increase by x%
90%*( 1+x%)= 1
Solution: x = 1/9
Therefore, the sales volume increased by11.11%compared with the original price.
3. The sum of the original unit prices of commodities A and B is 100 yuan. Due to market changes, a commodity decreased by 65,438+00%. B After the price adjustment of commodities rose by 5%, the sum of the unit prices of the two commodities rose by 2%. What are the original unit prices of A and B respectively?
If the original unit price of commodity A is X yuan, then B is100-X.
( 1- 10%)X+( 1+5%)( 100-X)= 100( 1+2%)
The result x = one in X=20 yuan.
100-20=80 B
4. The number of people in Workshop A is 30 less than 4/5 of Workshop B. If 10 people are transferred from Workshop B to Workshop A, then the number of people in Workshop A is 3/4 of Workshop B. Find the original number of people in each workshop.
There are x people in workshop B. According to the equality of the total number, the equation is listed as follows:
X+4/5X-30 = X- 10+3/4(X- 10)
X=250
So the number of people in Workshop A is 250*4/5-30= 170.
Description:
The left side of the equation is adjusted first, and the right side of the equation is adjusted later.
5.A rides a bike from place A to place B, and B rides a bike from place B to place A, both of which move at a constant speed, so that they start at 8 o'clock in the morning, and they are still 36 kilometers apart at 10 in the morning, and 36 kilometers apart at noon 12. How can we find the distance between a and b? (Equation)
Let the distance between a and b be x.
x-(x/4)=x-72
x=288
Answer: The distance between A and B is 288.
6 ..A The length of cars A and B is 180m. If two trains travel relatively, it takes * * *12s from the time when the front meets the rear; If driving in the same direction, it takes 60 seconds from the front of car A to the rear of car B, and the speed remains unchanged. Find the speed of a car and b car.
The sum of the speeds of the two vehicles is [180 * 2]/12 = 30m/s.
Let the speed of a be x, then the speed of b is 30-X.
180*2=60[X-(30-X)]
X= 18
That is, the speed of car A is 18m/s and the speed of car B is12m/s..
7. Two candles of the same length, the thick one can burn for 3 hours and the thin one can burn for 8/3 hours. When the power goes out, two candles are lit at the same time, and when the phone calls in, they are blown out at the same time. It is twice as thick as it is thin, and the time of power failure is found.
Suppose the blackout time is X.
Let the total length be 1, then the coarse firing is 1/3 and the fine firing is 3/8.
1-X/3=2[ 1-3X/8]
X=2. Four
Is the power failure 2. Four hours.
1. A group plans to make a batch of "Chinese knots". If everyone does five, it will be nine more than planned. If everyone does four, it will be less than planned 15. How many team members are there? How many Chinese knots do they plan to make?
There are x members in the team.
5x=4x+ 15+9
5x-4x= 15+9
8. A middle school organizes a spring outing for junior one students. It was originally planned to rent a number of 45-seat buses, but 15 people had no seats. If you rent the same number of 60-seat buses and have one more, the rest will be just full. We want to ask
(1) What is the number of students in Grade One? How many 45-seat buses were originally planned to be rented?
Solution: Rent 45-seat bus X and 60-seat bus (x- 1).
45x+ 15=60(x- 1)
Solution: x=5 45x+ 15=240 (person)
The number of students in Grade One is 240.
It is planned to rent five 45-seat buses.
9. Input a batch of accounting statements into the computer. It takes 20 hours for Party A to do it alone, and it takes 12h for Party B to do it alone. Now Party A works alone for 4 hours, and the rest is done by both parties. How long will Party A and Party B cooperate?
Solutions; Set to XH
1/5+ 1/20X+ 1/ 12X = 1
8/60X=4/5
X=6
The cooperation time of A and B is 6H.
The sum of 10.A, B and C is 53, so the ratio of A to B is 4: 3, C is 2 less than B, B is () and C is ().
Let a be 4X. Then b is 3X. C is 3X-2.
4X+3X+3X-2=53
10X=53+2
10X=55
X=5.5
3X= 16.5
3X-2= 16.5-2= 14.5
B is 16.5 and c is 14.5.
1 1. The length of the thick candle is the same as that of the thin candle. The thick candle burns for 5 hours and the thin candle burns for 4 hours. After the power failure, two candles are lit at the same time and put out at the same time after a call. It was found that the length of a thick candle was four times that of a thin candle. How long is the power outage?
Set the power outage for x hours. The thick candle burns 1/5 per hour, and the thin candle burns 1/4 per hour.
1- 1/5X = 4( 1- 1/4)
1- 1/5X=4-X
- 1/5+X=4- 1
4/5X=3
X= 15/4
12. For three digits, the number at 100 is larger than the number at 10 by 1 0, and the number at the third digit is 3/2 smaller than the number at 10. If the order of the three digits is reversed, the sum of the three digits and the original three digits is 1 17 1. Find this three-digit number
Let ten digits be x.
Then100× (x+1)+10x+3x-2+100 * (x+1)+/kloc-0+.
simplify
424x= 1272
So: x=3
This three-digit number is 437.
13. Three classes in Grade One of Senior High School donated books to Hope Primary School, and one class collected books 152 volumes. The number of books donated by class two is the average of three classes, and the number of books donated by class three is 40% of the total number of books donated by grade three. How many books did Class Three donate?
Solution: Set up 2 classes to donate X copies.
3x= 152+x+3xX40%
3x= 152+x+6/5x
3x-x-6/5x= 152
4/5x= 152
X = 190...(2) Class
190X3=570 (Ben)
14. The distance between a and b is 3 1 km. An hour later, A rode a bicycle from A to B, and B rode a motorcycle from A to B. It was known that A was driving at a speed of 12 km, and B was driving at a speed of 28 km. How many hours will it take to catch up with A after B leaves?
Let b catch up with equations a and b x hours after departure.
12 (x+ 1) = 28 x = 0.75 hours, or 45 minutes.
15. A cargo ship has a deadweight of 400 tons and a volume of 860m^3. Now it has to carry two kinds of goods, pig iron and cotton. The volume per ton of pig iron is 0.3m^3, and the volume per ton of cotton is 4 cubic meters. How many tons of pig iron and cotton can be loaded to make full use of the load and volume of this ship?
X tons of iron and 400-X tons of cotton.
0.3x+4*(400-x)=860
X = 200t tons
The answer is 200 tons of iron and 200 tons of cotton each.
16. A computer company sells two brands of computers, A and B, and sold 2,200 computers the year before last. Last year, the number of computers sold by A increased by 6% compared with the previous year, and the number of computers sold by B decreased by 5% compared with the previous year. The total sales of the two computers increased by 1 10. How many computers did A and B sell the year before last?
Suppose that computer A sold X units and computer B sold 2200-X units the year before last.
Last year, computer A was 1.06x, and computer B was 0.95 (2200-x).
1.06 x+0.95 *(2200-x)= 2200+ 1 10
x=2000
Then there are 2000 computers A and 200 computers B.
17. The area above the earth is about 7 1 times of the land area, and the surface area of the earth is about 5 1 100 million square kilometers. How big is the land area on the earth? (accurate to 0. 1 100 million square kilometers)
Let the area of the land be x.
X+7 1/29X=5. 1
X= 1.479
That is, the land area is:1.500 million square kilometers.
18. Pour a long cylindrical glass (filled with water) with an internal diameter of 90 mm into a rectangular iron box with a ground diameter of 13 1 * 1 mm and an internal height of 81mm. When the iron box is filled with water, how much does the water level in the glass drop?
Let the descending height be x.
The volume of falling water is equal to the volume of water in the iron box.
3. 14 * 45 * 45 * X = 13 1 * 13 1 * 8 1
X=2 18.6
The water level dropped by 2 18.6 mm.
19. A cylindrical glass with an inner diameter of 120mm and a cylindrical glass plate with an inner diameter of 300mm and an inner height of 32mm can hold the same amount of water. What is the internal height of the glass?
A cylindrical glass with an inner diameter of 120mm and a cylindrical glass plate with an inner diameter of 300mm and an inner height of 32mm can hold the same amount of water.
So the volumes of the two containers are equal.
The volume of a cylindrical glass disk with an inner diameter of 300mm and an inner height of 32mm.
V=π(300/2)^2*32=720000π
Let the internal height of the glass be x.
therefore
X*π( 120/2)^2=720000π
X = 200mm mm
20. Pour the full bucket of water in a cylindrical bucket with an inner diameter of 200mm into a rectangular iron box with internal length, width and height of 300mm, 300mm and 80mm respectively, and just fill it up. Find the water height of cylindrical bucket? (accurate to the millimeter. Dispatch 3. 14)
Let the height of the barrel be x.
3. 14 * 100 * 100 * X = 300 * 300 * 80
X=229
That is, the height of the bucket is 229 mm