1.2 ÷ 3 = 0.4km original working efficiency.
100 m = 0. 1 km
(3.3- 1.2)÷(0.4-0. 1)
=2. 1÷0.3
= 7 days remaining.
7+3= 10 days
Answer: It takes 10 days to dig this canal.
The beverage factory produced a batch of drinks. The original plan is to produce 3.5 tons a day, which can be completed on schedule. Due to the renewal of equipment, the daily output increased by 1.5 tons, so the task was completed in only 14 days, a few days earlier than originally planned.
(3.5+ 1.5)× 14÷3.5
=70÷3.5
=20 days The number of days originally planned.
20- 14=6 days
A: This was completed six days ahead of schedule.
3. The machinery factory has 63.5 tons of steel, and first trial-produced 10 machines, each with 0.75 tons of steel. After improving the design, each machine saves 50 kilograms of steel. How many machines can this batch of steel make?
50 kg =0.05 ton
(63.5-0.75× 10)÷(0.75-0.05)
=56÷0.7
80 machines that can be made of surplus steel.
10+80=90 sets
A: This batch of steel can make 90 machines.
The original cinema has 25 rows of seats, with 36 seats in each row. After the expansion, it will be 5 rows with 6 seats in each row. How many more people can we do after the expansion? Answer in two ways.
Method 1:
25×36+(36+6)×5
=900+2 10
= 1 1 10 people
Method two,
(25+5)×36+6×5
= 1080+30
= 1 1 10 people
A: After the expansion, 1 1 10 people can be added.
5. The transportation company contracted to transport 2,500 pieces of glass, and agreed that the freight for each piece was 0 4 yuan. If one piece is damaged, the freight of this glass will be deducted and 6 yuan will be compensated. As a result, the transportation team got the freight from 940 yuan. Q: How many pieces of glass were broken? Tell the content of each calculation step.
2,500× 0.4 =10,000 yuan, and the freight payable without damage.
1000-940= freight 60 yuan is undercharged.
0.4+3.6 = less freight 4 yuan for each piece of glass damaged.
60÷4= 15 yuan
15 piece of glass was broken.
6. A worker produces machine parts for 8 hours on the first day. The next day, it will produce 5 hours, and the next day, it will produce 6 more parts per hour than the first day. Because of time, the next day was 60 less than the first day. How many parts are produced every day?
Solution 1: 5 hours the next day is more than 5 hours the first day;
6×5=30 (piece)
The second day produced 60 fewer than the first day.
30+60=90 (pieces) is the quantity that can be produced for 3 hours with the efficiency of the first day.
So the first day, a * * * came into being.
90÷3×8=240 (pieces)
It was born the next day.
240-60= 180 (piece)
A: 240 pieces were produced on the first day, and 180 pieces were produced on the second day.
Solution 2: Production of X pieces per hour on the first day, and then production of (X+6) pieces per hour on the second day.
8×X-5×(x+6)=60。
x=30，
So the first day of production: 8×30=240,
Production the next day: (30+6)×5= 180.
A: 240 pieces were produced on the first day, and 180 pieces were produced on the second day.
7. There is a project that was originally planned to be completed in 12 days, with 42 people working 8 hours a day. After working for 7 days, 12 people change jobs and still work 8 hours a day. How many days will it take to complete the remaining projects? How many hours should I work every day if I want to finish the task according to the original planned date?
42× 12×8
=504×8
=4032 hours
42×7×8
=294×8
=2352 hours
4032-2352= 1680 hours 42- 12=30 people
1680÷(30×8)
= 1680÷240
Seven days A: It takes seven days to finish the rest of the work.
12-7=5 days
1680÷(30×5)
= 1680÷ 150
= 1 1.2 hours a: If you are required to finish the task according to the original planned date, you should work 1 1.2 hours a day.
8. The paper mill plans to produce 480 tons of paper every year, which is 1.2 times of the annual plan three months ahead of schedule. At this rate, how many tons of paper can this paper mill produce a year?
480× 1.2÷( 12-3)× 12
=576÷9× 12
=64× 12
=768 tons
This paper mill can produce 768 tons of paper a year.
9. Xiaoming's home is six kilometers away from school. He goes to school by bike every day. If he drives at a speed of four kilometers per hour, he will be five minutes late. How many kilometers an hour will he drive if he wants to get to school ten minutes before class?
5+10 =15min = 0.25h.
6÷4= 1.5 hours
1.5-0.25= 1.25 hours
6÷1.25 = 4.8km/h.
A: He will drive at a speed of 4.8 kilometers per hour.
10. There is a rectangular wasteland with a circumference of140m and a length of 2.5 times its width. If the length and width of this land are increased by five meters compared with that before reclamation, how many square meters will it increase?
140÷2÷( 1+2.5)
=70÷3.5
=20 meters wide
20×2.5=50 meters long.
(20+5)×(50+5)-20×50
=25×55- 1000
= 1375- 1000
=375 square meters
A: Then the increased land area is 375 square meters.
1 1, a rectangle, if its length is increased by five meters, or its width is increased by two meters, its area will increase by 60 square meters. What is the area of the original rectangle?
60 ÷ 5 =12m wide rectangle
60÷2=30 meters long rectangle
30×12 = 360m2
A: The original rectangular area was 360 square meters.
12. The circumference of a rectangle is 240 meters, and its length is twice its width. Find the area of a rectangle. Write down what each step is.
240 ÷ 2 =120m long widening
120 \\( 1+2) is twice as long as it is wide, and one length equals two widths.
= 120÷3
= 40m wide
40×2=80 meters long
80× 40 = 3200m2 area
A: The rectangular area is 3,200 square meters.