50 application problems and their answers in grade five;
1, A said to B, "When I was your age, you were only 4 years old." B said to A, "When I reach your present age, you will be 6 1 year old." How old are A and B now?
Solution: Suppose A is now X years old and B is now Y years old.
According to the meaning of the question:
x-y=y-4，
x-y=6 1-x
Solution: x=42, y=23.
A: A is 42 years old and B is 23 years old.
2. For a batch of manuscripts, if Party A finishes copying in 30 hours, Party B finishes copying in 20 hours, and 3 hours later is the remaining time for Party B to finish copying. How many hours does Party B need to copy? (column equation solution)
Setting b takes x hours.
1/30 * 3+X * 1/20 = 1
The solution is X= 18.
Party A and Party B ride motorcycles from AB, which is 60km apart, to a certain place. Party A is behind Party B. Party A rides 80 kilometers per hour and Party B rides 45 kilometers per hour. If A leaves 30 minutes earlier than B, how long will it take A to catch up with B?
1/2 * 80 = 40km
(60-40)/(80-45)=4/7
4/7+ 1/2= 15/ 14
Set x hours to catch up.
80X=45*(X- 1/2)+60
The solution is X= 15/ 14.
4. An airplane was originally scheduled to fly to its destination at the speed of 495 kilometers per hour, but due to the urgent task, the flight speed was increased to 660 kilometers per hour, and it arrived 1 hour in advance. What is the total flight distance?
X/495-X/660= 1
X= 1980
5. Eat 0.6 kg of soy sauce first, then eat the remaining 3/5, and there is 0.8 kg of soy sauce in the bottle. How many kilograms is this bottle of soy sauce?
(X-0.6)*( 1-3/5)=0.8
X=2.6
6. A truck and a bus walk with their backs to each other at the same time. When the truck travels for 5 hours and the bus travels for 6 hours, the distance between the two cars is 568 kilometers. As we all know, trucks are 8 kilometers faster than buses every hour. How many kilometers does this bus travel per hour?
If the bus is X, the truck is X+8.
5(X+8)+6X=568
X=48
7. Xin Li was riding a bicycle, and Liu Qiang was riding a motorcycle. At the same time, he started from two places 60 kilometers apart and walked in opposite directions. After meeting on the road, move on and turn your back. Six hours after their departure, they were 240 kilometers apart. As we all know, the speed of Xin Li is18km. How many kilometers does Liu Qiang drive every hour?
6( 18+X)=60+240
X=32
8. The distance between Party A and Party B is 22.5km, and they walk towards each other at the speed of 2.5km/h and 5km/h respectively. At the same time, the puppy brought by Party A ran to Party B at a speed of 7.5km/h, and the puppy returned to Party A immediately after meeting Party A, and then ran to Party B … until Party A and Party B met, the distance the puppy had traveled was calculated.
Because the walking time of the puppy = the walking time of both parties.
So the distance of the puppy = the time of the puppy * the speed of the puppy.
= Time of Party A and Party B * Puppy speed
=22.5/(2.5+5)*7.5
=22.5 km
9. Repair a section of road. A quarter of the total length was built on the first day and 90 meters on the second day. At this time,150m has not been repaired. How long is this road?
150+90 = 240m
1- 1/4=3/4
240 divided by 3/4=360 (meters)
10, the original price of a computer is 8000 yuan, and the current price is 6000 yuan. What percentage has the price been reduced?
Let's calculate what percentage of the original price it is now.
6000÷8000=75%
1-75%=25%
1 1, the average of a, b and c is 184, and the number of d is 64. What is the average of four numbers?
( 184×3+64)÷4= 154
12, five referees scored a gymnast, excluding a highest score and a lowest score, with an average score of 9.58. If only one highest score is removed, the average score is 9.46, and if only one lowest score is removed, the average score is 9.66. What are the highest and lowest scores?
9.58×3=28.74. The highest score: 9.46×4-28.74=9. 1.
Minimum score: 9.66×4-28.74=8.9.
13, China Mall paid 3.45 million yuan in profits and taxes in the first half of this year, completing 3/5 of the whole plan. How much profit and tax does this mall plan to pay throughout the year?
345 ÷ 3/5 = 575 (ten thousand yuan)
14. A food factory produced 1/2 tons of toffee in five days. According to this calculation, how many days will it take to produce 87 3/ 1 1 ton toffee?
87 3/11(1062/3 ÷ 5 and 1/2) = 4.5 (days)
15, average age of Party A and Party B 18, average age of Party B and Party C/20, average age of Party A, Party B and Party C 16. How old are A, B and C?
Three people * * *: 18+20+ 16 = 54 (years old)
A: 54-20×2= 14 (years old)
B: 54- 16×2=22 (years old)
C: 54- 18×2= 18 (years old)
16, Party A and Party B cooperate for 3 hours to produce 165 parts. If they work 8 hours respectively, Party A will produce 40 more parts than Party B.. How many parts do Party A and Party B produce per hour?
Answer: (165÷3+40)÷8 ÷2=30 (pieces)
B: 165÷3-30=25 (pieces)
17, two original warehouses, A and B, with 350 tons of grain. If 9 1 ton is shipped from warehouse A and 80 tons is shipped from warehouse B, then the inventory of warehouse B is 6 tons more than that of warehouse A. How many tons are there in warehouse A and warehouse B respectively?
A original: (350-91+80-6) ÷ (1+1/2)+91= 313 (ton)
B original: 350-3 13=37 (ton)
18, the bus and the truck travel in opposite directions from Station A and bilibili respectively. The bus takes 3 hours, and the speed of the truck is 60 kilometers per hour. After 72 kilometers, it will meet the bus. How many kilometers is it between Station A and bilibili?
72 ÷ (1-72 ÷ 60 ÷ 3) =120 (km)
19, a class held a parent-teacher meeting and prepared teacups for each parent. As a result, five cups were missing, and then half of them were borrowed. At this time, 13 cup was added. How many parents attended the meeting?
(5+13) ÷1/2+5 = 41(person)
20. The machine tool factory used to know that each machine tool used steel 1.02 tons. After the improved design, each machine tool saves 0.65,438+02 tons compared with the original machine tool. How many machine tools can we make now?
1.02-0.12 =1(ton)
300× 1.02=306 (ton)
306 ÷ 1 = 306 (Taiwan Province)
2 1, Xiaoming bought six pencils and four exercise books at 0.68 yuan each and 0.24 yuan each. Xiao Ming paid 5 yuan money, how much should he get back?
0.68×4=2.72 (yuan)
0.24× 6 = 1.44 (yuan)
2.72+ 1.44=4. 16 (yuan)
5-4. 16=0.84 (yuan)
22. Two trains, A and B, leave from two places at the same time. The speed of train A is 80 kilometers per hour, and that of train B is 70 kilometers per hour. 12 hours later, the distance between the two trains is still 1 10 km. How many kilometers are there between these two places?
(80+70)× 12= 1800 (km)
1800+110 =1910 (km)
23. Guangming Paper Mill produced a batch of newsprint, which was originally planned to be completed in 28 days, with a daily output of 12.5 tons. Now it's finished three days ahead of schedule. How many tons are actually produced every day than originally planned?
28× 12.5 = 350 (ton)
28 3 = 25 days
350÷25= 14 (ton)
14-12.5 =1.5 (ton)
24. Li Shifu produced a batch of spare parts. Three days ago, 126 parts were produced. According to this calculation, it takes 12 days to complete the production task. How many parts are there in this batch?
126 ÷ 3 = 42 (pieces)
42× (12+3) = 630 (pieces)
25. The chemical fertilizer plant planned to produce 84 tons of chemical fertilizer in 30 days, but actually produced 0.2 tons more than planned every day. How many days did it actually finish the task ahead of schedule?
84÷30=2.8 (ton)
2.8+0.2=3 (ton)
84÷3=28 (days)
30-28=2 (days)
26, processing a batch of clothes, processing 300 sets a day, 16 days can be completed,
(1) If 400 sets are processed every day, how many days will it be completed in advance?
300× 16 = 4800 (set)
4800 ÷ 400 = 12 (days)
16- 12=4 (days)
(2) If 20 sets are processed every day, how many days can it be completed?
300+20=320 (set)
4800÷320= 15 (days)
(3) If it is to be completed five days in advance, how many sets will be processed every day?
16-5= 1 1 (days)
4800÷ 1 1 is about equal to 436 (sets).
27. A car factory planned to produce16,800 cars throughout the year, and as a result, the annual production task was completed two months ahead of schedule. At this rate, how many cars can be produced throughout the year?
16800÷ (10-2) =1680 sets.
1680×12 = 20160 sets.
28. A workshop of Xinfeng Agricultural Machinery Factory processes 2480 parts. Originally, 100 pieces were processed every day, and after working for 20 days, 120 pieces were processed every day. So we can finish the task in a few days.
100× 20 = 2000
2480-2000 = 480
480 ÷ 120 = 4 days
29. A clothing factory used to make a children's dress, using 2.2 meters of cloth at a time. Now the cutting method has been improved, and each set saves 0.2 meters of cloth. The cloth used to make 600 sets of this kind of clothes, how many sets can be made now?
600× 2.2 =1320m
2.2-0.2 = 2m
1320 ÷ 2 = 660 sets
30. There is a cube, 70 cm long, 50 cm wide and 45 cm high. What is the maximum volume of these cubes if they are to be cut into cubes of the same size?
70=2×5×7
50=2×5×5
45=3×3×5
The greatest common factor of 70, 50 and 45 is 5.
Therefore, the side length of the small cube is 5 cm.
The maximum volume of these cubes is 5× 5× 5 = 125 (cubic centimeter
3 1, a rope, cut his 1/4, which is exactly 14.4 meters. How long is the rope?
Rope length:14.4÷1/4 = 57.6m.
32, the school to carry out tree planting activities. 39 plants were planted in the sixth grade, and the number of plants planted in the fifth grade was sixth grade 12/ 13. The number of trees planted in grade four is 5/64 of that in grade five. How many trees have been planted?
Planting trees in grade 4: 39× 12/ 13×5/6=30 trees.
33. A batch of coal has taken away his 1/5, which is exactly 1/6 tons. Find out the total amount of this batch of coal.
1/6÷ (1-1/5) = 5/24 tons.
34. A bank originally planned to issue 50 million yuan of government bonds in 20 days, but completed 2/5 of the plan six days ago. According to this calculation, how many days can it finish the task ahead of schedule?
It takes 2/5:20 * 2/5 = 8 days to complete the original plan.
Now it takes 2/5: 8-6=2 days.
Now it takes 2÷2/5=5 days to complete the task.
Can be completed in advance: 20-5= 15 days?
35. A garment factory used to make a children's garment, and every time it was covered with a cloth of 2.2 meters. Now the cutting method has been improved, and each set saves 0.2 meters of cloth. The cloth used to make 600 sets of this kind of clothes, how many sets can be made now?
600× 2.2 =1320m
2.2-0.2 = 2m
1320 ÷ 2 = 660 sets
36, 1 rope MINUS 1/5, and then 5 meters, which is 3/20 shorter than the original. How long is the rope now?
x- 1/5x+5= 17/20x
4/5x+5= 17/20x
5= 1/20x
x= 100
So the rope is now 17/20* 100=85 meters long.
There are 68 students in Class Five (1). One afternoon, the boys in this class111and five girls took part in the school math competition. Those boys and girls who didn't take part in the competition were equal. How many boys and girls are there in this class?
There are x boys in this class.
Then there is an equation: (1-111) x = (68-x)-5.
10/ 1 1x=63-x
2 1/ 1 1x=63
x=63/(2 1/ 1 1)
x=33
68-33=35 (person)
There are 33 boys and 35 girls in this class.
38. Build an expressway. After completing the total length of 1/6, there is still125km from the midpoint. What is the total length of this highway?
125/(1/2-1/6) = 375 (km)
This highway is 375 kilometers long.
39. A steel pipe uses 2/5, which is exactly 5 meters. If it uses 1/3, how many meters will it use?
5/(2/5)= 12.5 (m) 12.5* 1/3=25/6 (m)
A: If you use 65438+ 0/3 of it, you will use 25/6 meters.
40. The fifth-grade students planted trees. 13 or 14 has just been finished in each group. How many students took part in planting trees in grade five?
13X 14= 192 people
Answer: At least 192 people participated in tree planting in the fifth grade.
4 1. Two cars ran out of the same place. One car has a speed of 3 1 km, and the other car has a speed of 44 km. How many minutes later, the two cars are 300 kilometers apart?
Equation:
Solution: Two cars meet after X point.
3 1X+44X=300
75X=300
X=4
4 hours =240 minutes
Answer: After 240 minutes, the distance between the two cars is 300 kilometers.
42. Two construction teams will * * excavate a tunnel with a length of 1 19 meters, and the two construction teams will construct from both ends respectively. Team A digs 4 meters every day, while Team B digs 3 meters every day. How many days does it take to dig the tunnel?
Solution: Set X days to dig tunnels.
3X+4X= 1 19
7X= 1 19
X= 17
Answer: 17 days, the tunnel was dug.
43. School chorus and dance team 140 people. There are six times as many people in the chorus as in the dance team. How many people are there in the dance team?
Solution: There are X people in the dance team.
6X+X= 140
7X= 140
X=20 people
A: There are 20 people in the dance team.
44. The two brothers walked from home to the gym at the same time, with a length of 1, 300m m. My brother walked 80 meters per minute, and my brother rode his bike to the gym at a speed of1.80 meters per minute, and will be right back. On the way, he met his brother. How many minutes did he walk?
1300X2=2600 meters
2600/( 180+80)
=2600/260
= 10 point
Answer: At this time, my brother left 10 minutes.
45. Trapezoidal cornfield, with upper bottom15m, lower bottom 24m and height18m. There are 9 corn plants per square meter on average. How many corn can be planted in this field?
( 15+24)x 18/2 = 35 1 m2
35 1X9=3 195 strain
A: This land can grow 3 159 maize plants.
The number of students in a class is less than 100. When waiting in line, there are five people, four people and three people in each row. How many people are there in this class?
5X4X3=60 people 60+ 1=6 1 person
A: There are 6 1 person in this class.
47. Li Jun has a box of chocolates, and the number of 7, 5 and 3 chocolates at a time is more than 1. How many chocolates are there in this box?
7X5X3= 105 capsules 105+ 1= 106 capsules.
There are at least 106 chocolates in this box.
48. Liming Primary School has a rectangular tunnel with a length of 15m and a width of 1.2m, which needs to be paved with square bricks. The designer prepared a square brick with a side length of 30cm. Please calculate: how many such bricks are needed? If each square brick is 3 yuan, how much will it cost to build this tunnel?
15m = 150 decimeter 1.2m = 12 decimeter 30cm =3 decimeter.
150x12 =1800 square decimeter 3X3=9 square decimeter.
1800/9=200 yuan 200X3=600 yuan.
Answer: We need 200 such square bricks, and we need 600 yuan.
49. There are two parallelogram experimental fields with the same area. One is 70 meters long, 45 meters high and the other is 90 meters long. What's your height?
70x 45 = 3 150 m2 3 150/90 = 35m
A: The height is 35 meters.
50. A batch of steel pipes are piled into a pile, with the bottom layer 10, the top layer 1 less 1 less, and the top layer 1 less. How many steel pipes are there in this batch?
10-5+ 1=6 floors (10+5)X6/2.
= 15X6/2
=90/2
=45 pieces
A: There are 45 steel pipes in this batch.