Solution: It takes X months for Team A to complete this task alone, and (x-3) months for Team B..
Column equation:
5/x+4/x+4/(x-3)+ 1/x = 1
Simplification: x 2-17x+30 = 0
x 1=2，x2= 15
Because x>5 and so 2 were abandoned, it took Team A 15 months to complete it alone.
Someone wants to finish the task of typing 3000 words. After typing 800 words, he accelerated his typing speed, typing 15 more words per minute than before, * * * it takes 1 hour to complete the task. How many words per minute after speeding up?
Solution: Let's set the speed and type x per minute instead of x- 15 per minute.
800/(x- 15)+2200/x=60
800 x/x(x- 15)+2200(x- 15)/x(x- 15)= 60
800 x+2200(x- 15)= 60 x(x- 15)
6x*x-390x+3300=0
Solution: x 1=55, x2= 10 (omitted).
Answer: After speeding up, type 55 words per minute.
The {Oil Market Report} issued by the National Energy Administration on June 5438+ 10, 2004 predicts that China's annual oil consumption will continue to increase on the basis of 2003, reaching 300 million tons at most, and will become the second largest oil consumer in the world. As we all know, the annual oil consumption of China in 2003 was about 373 million tons. If the annual oil consumption in Tian Yue is 10000 barrels (1 ton is about 7.3 barrels), what is the average daily oil consumption in China in 2004?
According to the topic, the annual oil consumption of China in 2004 was 373 million tons to 673 million tons.
Let the average daily fuel consumption of China in 2004 be X.
Then the minimum xmin = 373000000 * 7.3/365/10000 = 7.46 million barrels.
Maximum xmax = 673 million * 7.3/365/10000 =13.46 million barrels.
Therefore, the average daily oil consumption in China in 2004 was between 7.46 million barrels and 6.5438+0346 million barrels.
AB is 64 kilometers apart. Party A and Party B walk in opposite directions from AB respectively. Party A walks 40 minutes later than Party B, if Party A walks 40 minutes later than Party B, and if Party A rides 4 kilometers more than Party B every hour, then they meet at the midpoint of AB, and find out how many kilometers Party A and Party B ride every hour.
Suppose the speed of a is X km/h, then according to the meaning of the question, it can be concluded that the speed of b is
(X-4) km/h.
32/X+2/3=32/(X-4)
The solution is X= 16, X=- 12 (abbreviated).
The renovation of the blackboard during the teacher's school holiday must be completed within the specified date. If it is completed by the engineering team, it will be completed before the date. If it is done by the B engineering team, it will be three days later than the stipulated date. As a result, the two teams worked together for 2 days, and the rest were all done by B alone, just within the stipulated date.
Because it takes X days for Party A to do it alone, it will complete 1/x of the total workload every day.
B It takes (x+3) days for one person to do it, and 1/(x+3) of the total workload is completed every day.
Set by topic:
{ 1-2[( 1/x)+ 1/(x+3)]=(x-2)( 1/(x+3))。
[x(x+3)-2(x+3)-2x]/x(x+3)= x(x-2)/x(x+3)。 ∵ x (x+3) ≠ 0, two sides of the equation.
∴x^2+3x-2x-6-2x=x^2-2x ..
x=6。
A: The stipulated date is six days.
1 A store buys a batch of goods from a manufacturer at the price of 18 yuan. Shops can set their own prices, but the price department limits the price of each commodity to 25% of the purchase price. According to market research, the relationship between commodity price and sales volume is that if the price of each commodity is one yuan, it can sell (320- 10a) pieces. If the store intends to make a profit in 400 yuan, what should be the price of each commodity? How many pieces do you need to sell?
If the price of each commodity is one yuan, the price department will limit the price increase of each commodity to less than 25% of the purchase price, then A
If you buy (320- 10a) pieces, you can make a profit.
(a- 18)*(320- 10a)=- 10a^2+500a-5760
If the store plans to make a profit in 400 yuan,-10a 2+500a-5760 = 400.
A 2-50a+6 16 = 0，a = 22，a = 28。 5)
So we should price 22 yuan.
Need to sell at this time.
320- 10*22= 100 pieces
In recent years, a city has carried out "four links, five changes and six villages" as the carrier. The new rural construction activities characterized by ecological civilization have achieved remarkable results. Please look at the following dialogue.
Leader: There are 13233 natural villages in the city. In 2006, 23 15 eco-civilized villages have been built. It is planned that the number of eco-civilized villages in the city will reach 24.4% of the total number of natural villages in 2008.
Citizen: According to this plan, what is the average annual growth rate of eco-civilized villages from 2006 to 2008?
2. Solution: Suppose the average annual growth rate of ecological civilization villages is,
According to the meaning of the question, you must
Solution: (irrelevant to the topic, give up)
A: The average annual growth rate of eco-civilized villages is about 18. 1%.
In the "Love Wenchuan" donation activity, a classmate made statistics on the donations of Class A and Class B, and got the following three pieces of information:
Message 1: Class A donated to 300 yuan, and Class B donated 232 yuan;
Information 2: The average donation amount of Class B is 4/5 of that of Class A;
Message 3: Class A has two more people than Class B.
According to the above three pieces of information, please calculate the average donation of everyone in Class A.
Solution: On average, each Class A donation is RMB X.
Then b is 4x/5 yuan.
So A has 300/x people and B has 232/(4x/5) people.
According to the meaning of the question.
300/x-232/(4x/5)=2
300/x-290/x=2
10/x=2
x=5
A: 5 yuan per person?