Mental Maths Questions and Answers: Direct and Inverse Proportion | Mental Mathematics for Class 8 PDF Download

 Page 1


  
 
 
Direct and Inverse Proportions 
Points to Remember 
? In direct proportion, two quantities x and y increase or decrease together, the 
ratio of their corresponding values remains constant. 
i.e. 
?? ?? ?? ?? =
?? ?? ?? ?? = ?? 
Or
?? ?? ?? ?? =
?? ?? ?? ?? = ?? , where ?? is a positive number. 
e.g. Ramesh covers a distance of 4km in 2 hours and with same speed he can cover 8 
km in 4 hours or we can say when time is increased, distance also increases so it 
is a case of direct proportion. 
? In inverse proportion, increase in a quantity x, causes a proportional decrease in 
quantity y and vice versa, the product of their corresponding values remains 
constant. 
i.e. ?? ?? ?? ?? = ?? ?? ?? ?? = ?? 
Or 
?? ?? ?? ?? =
?? ?? ?? ?? = ?? , where ?? is a positive number. 
e.g. Four men complete a construction work in 10 days and 5 men complete the same 
work in 8 days. When we increase the number of workers, the number of days to 
complete same work decreases so it is a case of inverse proportion. 
 
QUESTIONS 
1. ‘x’ and ‘y’ are directly proportional to each other. If ?? ?? = ???? , ?? ?? = ?? , ?? ?? = ?? 
then find ?? ?? . 
2. A person can build a wall in 10 days. What fraction of the wall will be completed 
in 2 days? 
3. A lady covers a distance of 75 m in 60 steps. What distance will she cover in 320 
steps? 
4. It takes 2 hours for 6 pipes to fill a tank. How much time will be needed to fill 10 
such tanks if 12 pipes are used? 
5. A train is moving at 150 kilometer/hour. How far will it go in 20 minutes? 
6. The scale of a map is 1:200000. What is the actual distance of 5 cm on the map? 
Page 2


  
 
 
Direct and Inverse Proportions 
Points to Remember 
? In direct proportion, two quantities x and y increase or decrease together, the 
ratio of their corresponding values remains constant. 
i.e. 
?? ?? ?? ?? =
?? ?? ?? ?? = ?? 
Or
?? ?? ?? ?? =
?? ?? ?? ?? = ?? , where ?? is a positive number. 
e.g. Ramesh covers a distance of 4km in 2 hours and with same speed he can cover 8 
km in 4 hours or we can say when time is increased, distance also increases so it 
is a case of direct proportion. 
? In inverse proportion, increase in a quantity x, causes a proportional decrease in 
quantity y and vice versa, the product of their corresponding values remains 
constant. 
i.e. ?? ?? ?? ?? = ?? ?? ?? ?? = ?? 
Or 
?? ?? ?? ?? =
?? ?? ?? ?? = ?? , where ?? is a positive number. 
e.g. Four men complete a construction work in 10 days and 5 men complete the same 
work in 8 days. When we increase the number of workers, the number of days to 
complete same work decreases so it is a case of inverse proportion. 
 
QUESTIONS 
1. ‘x’ and ‘y’ are directly proportional to each other. If ?? ?? = ???? , ?? ?? = ?? , ?? ?? = ?? 
then find ?? ?? . 
2. A person can build a wall in 10 days. What fraction of the wall will be completed 
in 2 days? 
3. A lady covers a distance of 75 m in 60 steps. What distance will she cover in 320 
steps? 
4. It takes 2 hours for 6 pipes to fill a tank. How much time will be needed to fill 10 
such tanks if 12 pipes are used? 
5. A train is moving at 150 kilometer/hour. How far will it go in 20 minutes? 
6. The scale of a map is 1:200000. What is the actual distance of 5 cm on the map? 
  
 
7. Four pipes can fill a tank in 1 hour 20 minutes. How long will it take to fill the 
tank if 8 pipes are used? 
8. If 15 tailors can stitch a dress in 24 days, how long will 9 tailors take to stitch the 
same dress? 
9. Bus is travelling at an average speed of 55 km/ hour. How much distance would 
it cover in 12 minutes? 
10. 20 women can whitewash a building in 26 days. In how many days can 52 women 
whitewash the same building? 
11. 72 chocolates are packed in 8 boxes of same size. How many boxes are required 
for 360 chocolates? 
12. 6 men can construct a wall in 5 days. If 10 men are employed, find the number of 
days in which the similar wall can be constructed? 
13. A carpenter prepares 36 tables in 8 days. In how many days would he prepare 27 
such tables? 
14. If 560 notebooks cost  ` 3920, find the cost of 6 dozen notebooks. 
15. 10 women can do a job in 20 days. In how many days can 20 women do the same 
job? 
16. What will happen to the area of a square if the length of each side is doubled? 
17. A scooter travels 44 kilometer on 4 litres of petrol. How far will it go in 13 litres 
of petrol? 
18. In a fort, there is food for 240 soldiers that is enough for 10 days. If 40 soldiers 
left the fort, then for how many days the food will last? 
19. Nine bags of fertilizers weigh 639 kilograms. What is the weight of 4 bags? 
20. Ravi takes 40 minutes to reach the school with a speed of 4 km/hr. If he walks 
with a speed of 5 km/hr., how much time will he now take to reach the school? 
21. If the cost of 20 m cloth is ` 420, how much cloth can be bought for ` 105? 
22. Out of 45 students, 9 are absent. What is the ratio of present students to absent 
ones? 
23. The weekly consumption of potatoes in a hostel with 640 students is 160 
kilogram. Find the consumption if the number of students become 800. 
24. If the cost of two dozen pens is ` 60, what will be the cost of 60 pens? 
25. 6 taps can fill a water tank in 90 minutes. How many taps can fill the same water 
tank in 30 minutes? 
Page 3


  
 
 
Direct and Inverse Proportions 
Points to Remember 
? In direct proportion, two quantities x and y increase or decrease together, the 
ratio of their corresponding values remains constant. 
i.e. 
?? ?? ?? ?? =
?? ?? ?? ?? = ?? 
Or
?? ?? ?? ?? =
?? ?? ?? ?? = ?? , where ?? is a positive number. 
e.g. Ramesh covers a distance of 4km in 2 hours and with same speed he can cover 8 
km in 4 hours or we can say when time is increased, distance also increases so it 
is a case of direct proportion. 
? In inverse proportion, increase in a quantity x, causes a proportional decrease in 
quantity y and vice versa, the product of their corresponding values remains 
constant. 
i.e. ?? ?? ?? ?? = ?? ?? ?? ?? = ?? 
Or 
?? ?? ?? ?? =
?? ?? ?? ?? = ?? , where ?? is a positive number. 
e.g. Four men complete a construction work in 10 days and 5 men complete the same 
work in 8 days. When we increase the number of workers, the number of days to 
complete same work decreases so it is a case of inverse proportion. 
 
QUESTIONS 
1. ‘x’ and ‘y’ are directly proportional to each other. If ?? ?? = ???? , ?? ?? = ?? , ?? ?? = ?? 
then find ?? ?? . 
2. A person can build a wall in 10 days. What fraction of the wall will be completed 
in 2 days? 
3. A lady covers a distance of 75 m in 60 steps. What distance will she cover in 320 
steps? 
4. It takes 2 hours for 6 pipes to fill a tank. How much time will be needed to fill 10 
such tanks if 12 pipes are used? 
5. A train is moving at 150 kilometer/hour. How far will it go in 20 minutes? 
6. The scale of a map is 1:200000. What is the actual distance of 5 cm on the map? 
  
 
7. Four pipes can fill a tank in 1 hour 20 minutes. How long will it take to fill the 
tank if 8 pipes are used? 
8. If 15 tailors can stitch a dress in 24 days, how long will 9 tailors take to stitch the 
same dress? 
9. Bus is travelling at an average speed of 55 km/ hour. How much distance would 
it cover in 12 minutes? 
10. 20 women can whitewash a building in 26 days. In how many days can 52 women 
whitewash the same building? 
11. 72 chocolates are packed in 8 boxes of same size. How many boxes are required 
for 360 chocolates? 
12. 6 men can construct a wall in 5 days. If 10 men are employed, find the number of 
days in which the similar wall can be constructed? 
13. A carpenter prepares 36 tables in 8 days. In how many days would he prepare 27 
such tables? 
14. If 560 notebooks cost  ` 3920, find the cost of 6 dozen notebooks. 
15. 10 women can do a job in 20 days. In how many days can 20 women do the same 
job? 
16. What will happen to the area of a square if the length of each side is doubled? 
17. A scooter travels 44 kilometer on 4 litres of petrol. How far will it go in 13 litres 
of petrol? 
18. In a fort, there is food for 240 soldiers that is enough for 10 days. If 40 soldiers 
left the fort, then for how many days the food will last? 
19. Nine bags of fertilizers weigh 639 kilograms. What is the weight of 4 bags? 
20. Ravi takes 40 minutes to reach the school with a speed of 4 km/hr. If he walks 
with a speed of 5 km/hr., how much time will he now take to reach the school? 
21. If the cost of 20 m cloth is ` 420, how much cloth can be bought for ` 105? 
22. Out of 45 students, 9 are absent. What is the ratio of present students to absent 
ones? 
23. The weekly consumption of potatoes in a hostel with 640 students is 160 
kilogram. Find the consumption if the number of students become 800. 
24. If the cost of two dozen pens is ` 60, what will be the cost of 60 pens? 
25. 6 taps can fill a water tank in 90 minutes. How many taps can fill the same water 
tank in 30 minutes? 
  
 
26. If Aman reads 12 pages daily, he can complete a book in 15 days. How many 
days will it take to complete the book, if he reads 30 pages daily? 
 
27. A stock of food grains is enough for 600 students for 10 weeks. How long will the 
same stock last for 240 students? 
28. If the length of a rectangle is halved, what change should be made in its breadth 
so that its area remains the same? 
29. 12 workers can construct a room in 7 hours. How many workers will be needed 
in all for constructing the same sized room in 2 hours? 
30. Aman and Abhinav can complete a project in 24 days. Aman alone can do the 
same task in 36 days. How much time will Abhinav take alone to complete the 
same project? 
31. In a library, 189 copies of a certain book require a shelf length of 3.78 meter. 
How many copies of the same book would occupy shelf length of 0.42 meter? 
32. Mohan is paid ` 2720 on working for eight days. If his total wages during a 
month is ` 6800, for how many days did he work? 
33. A train running at the speed of 108 kilometer/ hr passes a signal post in 10 
seconds. Find the length of the train in meters. 
34. If 30 stamps occupy an area of 75 cm
2
, how much area of paper is required for 
putting 330 stamps assuming that no area is wasted in between two stamps? 
35. Geet, Meet and Reet can do a work in 15, 6 and 10 days respectively. All the 
three together can finish four times of that work in how many days? 
36. If ???? = ???? = ???? ,then find?? : ?? : ?? . 
37. If 75 goats can graze a field in 13 days, how many goats will graze the same field 
in 25 days? 
38. Kavita can type a given assignment in 1 hour 30 minutes at a speed of 50 words 
per minute. Her friend Kareem can type the same assignment in 60 minutes. 
What would be Kareem’s typing speed? 
39. If 40 square metres of a carpet cost ` 241.60, find the cost of 50 square metres of 
carpet. 
40. Reena, Meena and Teena can complete a job in 10, 12 and 15 days respectively. 
In how many days will they complete the work together? 
Page 4


  
 
 
Direct and Inverse Proportions 
Points to Remember 
? In direct proportion, two quantities x and y increase or decrease together, the 
ratio of their corresponding values remains constant. 
i.e. 
?? ?? ?? ?? =
?? ?? ?? ?? = ?? 
Or
?? ?? ?? ?? =
?? ?? ?? ?? = ?? , where ?? is a positive number. 
e.g. Ramesh covers a distance of 4km in 2 hours and with same speed he can cover 8 
km in 4 hours or we can say when time is increased, distance also increases so it 
is a case of direct proportion. 
? In inverse proportion, increase in a quantity x, causes a proportional decrease in 
quantity y and vice versa, the product of their corresponding values remains 
constant. 
i.e. ?? ?? ?? ?? = ?? ?? ?? ?? = ?? 
Or 
?? ?? ?? ?? =
?? ?? ?? ?? = ?? , where ?? is a positive number. 
e.g. Four men complete a construction work in 10 days and 5 men complete the same 
work in 8 days. When we increase the number of workers, the number of days to 
complete same work decreases so it is a case of inverse proportion. 
 
QUESTIONS 
1. ‘x’ and ‘y’ are directly proportional to each other. If ?? ?? = ???? , ?? ?? = ?? , ?? ?? = ?? 
then find ?? ?? . 
2. A person can build a wall in 10 days. What fraction of the wall will be completed 
in 2 days? 
3. A lady covers a distance of 75 m in 60 steps. What distance will she cover in 320 
steps? 
4. It takes 2 hours for 6 pipes to fill a tank. How much time will be needed to fill 10 
such tanks if 12 pipes are used? 
5. A train is moving at 150 kilometer/hour. How far will it go in 20 minutes? 
6. The scale of a map is 1:200000. What is the actual distance of 5 cm on the map? 
  
 
7. Four pipes can fill a tank in 1 hour 20 minutes. How long will it take to fill the 
tank if 8 pipes are used? 
8. If 15 tailors can stitch a dress in 24 days, how long will 9 tailors take to stitch the 
same dress? 
9. Bus is travelling at an average speed of 55 km/ hour. How much distance would 
it cover in 12 minutes? 
10. 20 women can whitewash a building in 26 days. In how many days can 52 women 
whitewash the same building? 
11. 72 chocolates are packed in 8 boxes of same size. How many boxes are required 
for 360 chocolates? 
12. 6 men can construct a wall in 5 days. If 10 men are employed, find the number of 
days in which the similar wall can be constructed? 
13. A carpenter prepares 36 tables in 8 days. In how many days would he prepare 27 
such tables? 
14. If 560 notebooks cost  ` 3920, find the cost of 6 dozen notebooks. 
15. 10 women can do a job in 20 days. In how many days can 20 women do the same 
job? 
16. What will happen to the area of a square if the length of each side is doubled? 
17. A scooter travels 44 kilometer on 4 litres of petrol. How far will it go in 13 litres 
of petrol? 
18. In a fort, there is food for 240 soldiers that is enough for 10 days. If 40 soldiers 
left the fort, then for how many days the food will last? 
19. Nine bags of fertilizers weigh 639 kilograms. What is the weight of 4 bags? 
20. Ravi takes 40 minutes to reach the school with a speed of 4 km/hr. If he walks 
with a speed of 5 km/hr., how much time will he now take to reach the school? 
21. If the cost of 20 m cloth is ` 420, how much cloth can be bought for ` 105? 
22. Out of 45 students, 9 are absent. What is the ratio of present students to absent 
ones? 
23. The weekly consumption of potatoes in a hostel with 640 students is 160 
kilogram. Find the consumption if the number of students become 800. 
24. If the cost of two dozen pens is ` 60, what will be the cost of 60 pens? 
25. 6 taps can fill a water tank in 90 minutes. How many taps can fill the same water 
tank in 30 minutes? 
  
 
26. If Aman reads 12 pages daily, he can complete a book in 15 days. How many 
days will it take to complete the book, if he reads 30 pages daily? 
 
27. A stock of food grains is enough for 600 students for 10 weeks. How long will the 
same stock last for 240 students? 
28. If the length of a rectangle is halved, what change should be made in its breadth 
so that its area remains the same? 
29. 12 workers can construct a room in 7 hours. How many workers will be needed 
in all for constructing the same sized room in 2 hours? 
30. Aman and Abhinav can complete a project in 24 days. Aman alone can do the 
same task in 36 days. How much time will Abhinav take alone to complete the 
same project? 
31. In a library, 189 copies of a certain book require a shelf length of 3.78 meter. 
How many copies of the same book would occupy shelf length of 0.42 meter? 
32. Mohan is paid ` 2720 on working for eight days. If his total wages during a 
month is ` 6800, for how many days did he work? 
33. A train running at the speed of 108 kilometer/ hr passes a signal post in 10 
seconds. Find the length of the train in meters. 
34. If 30 stamps occupy an area of 75 cm
2
, how much area of paper is required for 
putting 330 stamps assuming that no area is wasted in between two stamps? 
35. Geet, Meet and Reet can do a work in 15, 6 and 10 days respectively. All the 
three together can finish four times of that work in how many days? 
36. If ???? = ???? = ???? ,then find?? : ?? : ?? . 
37. If 75 goats can graze a field in 13 days, how many goats will graze the same field 
in 25 days? 
38. Kavita can type a given assignment in 1 hour 30 minutes at a speed of 50 words 
per minute. Her friend Kareem can type the same assignment in 60 minutes. 
What would be Kareem’s typing speed? 
39. If 40 square metres of a carpet cost ` 241.60, find the cost of 50 square metres of 
carpet. 
40. Reena, Meena and Teena can complete a job in 10, 12 and 15 days respectively. 
In how many days will they complete the work together? 
  
 
41. A journey by car takes 45 minutes at 40 kilometer/ hour. How fast must a car go 
to undertake the same journey in 25 minutes? 
42. If 30 women can repair a road in 48 days, how long will 18 women take to repair 
the same road? 
43. Rekha can drive to Gwalior in eight hours at 60 kilometer per hour. How long 
will Ravi take to drive to Gwalior if his speed is 40 kilometer per hour? 
44. The speed of a train 125 m long is 45 kilometer/hr. How much time will it take to 
pass a platform 1375m long? 
45. 6 monkeys take 6 minutes to eat 6 bananas. How many minutes would 10 
monkeys will take to eat 10 bananas if their speed of eating is equal? 
46. How long will an athlete take to run around a rectangular park measuring 
?????? × ?????? ,if she runs at a speed of 3 m/sec? 
47. Two bus drivers start from same place in opposite directions. One goes towards 
north at 36 kilometer/ hour and other goes towards south at a speed of 40 
kilometer/ hour. What time did they to be 190 kilometer apart? 
48. Satyam has enough money to buy 60 oranges at ` 5 per orange. How many 
oranges can he buy if the price is increased by rupees 1 per orange? 
49. The cost of 32 packets of Vim each weighing 900 gram is `56. What will be the 
cost of 27 packets if each packet weighs 1 kilogram? 
50. Abha cycles to her school at an average speed of 15 kilometer per hour. It takes 
20 minutes to reach the school in time. At what speed should she cycle if she has 
to reach 5 minutes earlier? 
 
 
 
 
 
  
Page 5


  
 
 
Direct and Inverse Proportions 
Points to Remember 
? In direct proportion, two quantities x and y increase or decrease together, the 
ratio of their corresponding values remains constant. 
i.e. 
?? ?? ?? ?? =
?? ?? ?? ?? = ?? 
Or
?? ?? ?? ?? =
?? ?? ?? ?? = ?? , where ?? is a positive number. 
e.g. Ramesh covers a distance of 4km in 2 hours and with same speed he can cover 8 
km in 4 hours or we can say when time is increased, distance also increases so it 
is a case of direct proportion. 
? In inverse proportion, increase in a quantity x, causes a proportional decrease in 
quantity y and vice versa, the product of their corresponding values remains 
constant. 
i.e. ?? ?? ?? ?? = ?? ?? ?? ?? = ?? 
Or 
?? ?? ?? ?? =
?? ?? ?? ?? = ?? , where ?? is a positive number. 
e.g. Four men complete a construction work in 10 days and 5 men complete the same 
work in 8 days. When we increase the number of workers, the number of days to 
complete same work decreases so it is a case of inverse proportion. 
 
QUESTIONS 
1. ‘x’ and ‘y’ are directly proportional to each other. If ?? ?? = ???? , ?? ?? = ?? , ?? ?? = ?? 
then find ?? ?? . 
2. A person can build a wall in 10 days. What fraction of the wall will be completed 
in 2 days? 
3. A lady covers a distance of 75 m in 60 steps. What distance will she cover in 320 
steps? 
4. It takes 2 hours for 6 pipes to fill a tank. How much time will be needed to fill 10 
such tanks if 12 pipes are used? 
5. A train is moving at 150 kilometer/hour. How far will it go in 20 minutes? 
6. The scale of a map is 1:200000. What is the actual distance of 5 cm on the map? 
  
 
7. Four pipes can fill a tank in 1 hour 20 minutes. How long will it take to fill the 
tank if 8 pipes are used? 
8. If 15 tailors can stitch a dress in 24 days, how long will 9 tailors take to stitch the 
same dress? 
9. Bus is travelling at an average speed of 55 km/ hour. How much distance would 
it cover in 12 minutes? 
10. 20 women can whitewash a building in 26 days. In how many days can 52 women 
whitewash the same building? 
11. 72 chocolates are packed in 8 boxes of same size. How many boxes are required 
for 360 chocolates? 
12. 6 men can construct a wall in 5 days. If 10 men are employed, find the number of 
days in which the similar wall can be constructed? 
13. A carpenter prepares 36 tables in 8 days. In how many days would he prepare 27 
such tables? 
14. If 560 notebooks cost  ` 3920, find the cost of 6 dozen notebooks. 
15. 10 women can do a job in 20 days. In how many days can 20 women do the same 
job? 
16. What will happen to the area of a square if the length of each side is doubled? 
17. A scooter travels 44 kilometer on 4 litres of petrol. How far will it go in 13 litres 
of petrol? 
18. In a fort, there is food for 240 soldiers that is enough for 10 days. If 40 soldiers 
left the fort, then for how many days the food will last? 
19. Nine bags of fertilizers weigh 639 kilograms. What is the weight of 4 bags? 
20. Ravi takes 40 minutes to reach the school with a speed of 4 km/hr. If he walks 
with a speed of 5 km/hr., how much time will he now take to reach the school? 
21. If the cost of 20 m cloth is ` 420, how much cloth can be bought for ` 105? 
22. Out of 45 students, 9 are absent. What is the ratio of present students to absent 
ones? 
23. The weekly consumption of potatoes in a hostel with 640 students is 160 
kilogram. Find the consumption if the number of students become 800. 
24. If the cost of two dozen pens is ` 60, what will be the cost of 60 pens? 
25. 6 taps can fill a water tank in 90 minutes. How many taps can fill the same water 
tank in 30 minutes? 
  
 
26. If Aman reads 12 pages daily, he can complete a book in 15 days. How many 
days will it take to complete the book, if he reads 30 pages daily? 
 
27. A stock of food grains is enough for 600 students for 10 weeks. How long will the 
same stock last for 240 students? 
28. If the length of a rectangle is halved, what change should be made in its breadth 
so that its area remains the same? 
29. 12 workers can construct a room in 7 hours. How many workers will be needed 
in all for constructing the same sized room in 2 hours? 
30. Aman and Abhinav can complete a project in 24 days. Aman alone can do the 
same task in 36 days. How much time will Abhinav take alone to complete the 
same project? 
31. In a library, 189 copies of a certain book require a shelf length of 3.78 meter. 
How many copies of the same book would occupy shelf length of 0.42 meter? 
32. Mohan is paid ` 2720 on working for eight days. If his total wages during a 
month is ` 6800, for how many days did he work? 
33. A train running at the speed of 108 kilometer/ hr passes a signal post in 10 
seconds. Find the length of the train in meters. 
34. If 30 stamps occupy an area of 75 cm
2
, how much area of paper is required for 
putting 330 stamps assuming that no area is wasted in between two stamps? 
35. Geet, Meet and Reet can do a work in 15, 6 and 10 days respectively. All the 
three together can finish four times of that work in how many days? 
36. If ???? = ???? = ???? ,then find?? : ?? : ?? . 
37. If 75 goats can graze a field in 13 days, how many goats will graze the same field 
in 25 days? 
38. Kavita can type a given assignment in 1 hour 30 minutes at a speed of 50 words 
per minute. Her friend Kareem can type the same assignment in 60 minutes. 
What would be Kareem’s typing speed? 
39. If 40 square metres of a carpet cost ` 241.60, find the cost of 50 square metres of 
carpet. 
40. Reena, Meena and Teena can complete a job in 10, 12 and 15 days respectively. 
In how many days will they complete the work together? 
  
 
41. A journey by car takes 45 minutes at 40 kilometer/ hour. How fast must a car go 
to undertake the same journey in 25 minutes? 
42. If 30 women can repair a road in 48 days, how long will 18 women take to repair 
the same road? 
43. Rekha can drive to Gwalior in eight hours at 60 kilometer per hour. How long 
will Ravi take to drive to Gwalior if his speed is 40 kilometer per hour? 
44. The speed of a train 125 m long is 45 kilometer/hr. How much time will it take to 
pass a platform 1375m long? 
45. 6 monkeys take 6 minutes to eat 6 bananas. How many minutes would 10 
monkeys will take to eat 10 bananas if their speed of eating is equal? 
46. How long will an athlete take to run around a rectangular park measuring 
?????? × ?????? ,if she runs at a speed of 3 m/sec? 
47. Two bus drivers start from same place in opposite directions. One goes towards 
north at 36 kilometer/ hour and other goes towards south at a speed of 40 
kilometer/ hour. What time did they to be 190 kilometer apart? 
48. Satyam has enough money to buy 60 oranges at ` 5 per orange. How many 
oranges can he buy if the price is increased by rupees 1 per orange? 
49. The cost of 32 packets of Vim each weighing 900 gram is `56. What will be the 
cost of 27 packets if each packet weighs 1 kilogram? 
50. Abha cycles to her school at an average speed of 15 kilometer per hour. It takes 
20 minutes to reach the school in time. At what speed should she cycle if she has 
to reach 5 minutes earlier? 
 
 
 
 
 
  
  
 
ANSWERS 
Question No. Answer Question No. Answer 
1.          ?? ?? = ?? 27. 25 weeks 
2.           ?? ?? / 28. 
Breadth should be doubled 
3.  400m 29. 42 workers 
4.  10 hrs 30. 72 days 
5.  50 kilometer 31. 21 copies 
6.  10 kilometer 32. 20 days 
7.  40 min 33. 300 m 
8.  40 days 34. 825 cm
2
 
9.  11 kilometer 35. 12 days 
10.  10 days 36. 6:4:3 
11.  40 boxes 37. 39 goats 
12.  3 days 38. 75 words/ min 
13.  6 days 39. ` 302 
14.  ` 504 40. 4 days 
15.  10 days 41. 72 kilometer/ hour 
16.  
Area will become its 
4 times 
42. 80 days 
17.  143 kilometer 43. 12 hours 
18.  12 days 44. 2 minutes 
19.  284 kilogram 45. 6 minutes 
20.  32 minutes 46. 60 seconds/ 1 min 
21.  5 meter 47. ?? ?? ?? ?????? ???? ?? ???? ???? ?????? 
22.  4:1 48. 50 oranges 
23.  200 kilogram 49. `52.50 
24.  `150 50. 20 kilometer/hr 
25.  18 taps   
26.  6 days