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 Page 1


Q u e s t i o n : 1
If 15 oranges cost Rs 110,  what do 39 oranges cost?
S o l u t i o n :
Cost of 15 oranges = Rs 110
Cost of 1 orange = Rs 
110
15
? Cost of 39 oranges = Rs 
110
15
×39
= Rs 286
Q u e s t i o n : 2
If 8 kg sugar costs Rs 260, how much sugar can be bought for Rs 877.50?
S o l u t i o n :
Amount of sugar bought for Rs 260 = 8 kg
Amount of sugar bought for Re 1 = 
8
260
kg
Now, amount of sugar bought for Rs 877.50 = 
8
260
×877. 50
kg = 27 kg
? 27 kg of sugar can be bought for Rs 877.50.
Q u e s t i o n : 3
The cost of 37 m of silk is Rs 6290. What length of this silk can be purchased for 4420?
S o l u t i o n :
Length of the silk purchased for Rs 6290  = 37 m
Length of the silk purchased for  Re 1= 
37
6290
m
Now, length of the silk purchased for Rs 4,420 = 
37
6290
×4420
m = 26 m
? 26 m of silk can be purchased for Rs 4,420.
Q u e s t i o n : 4
A worker is paid Rs 1110 for 6 days. If his total wages during a month are Rs 4625, for how many days did he work?
S o l u t i o n :
Number of days for which a worker is paid Rs 1,110 = 6
Number of days for which a worker is paid Re 1 = 
6
1110
days
Now, number of days for which a worker is paid Rs 4625=
6
1110
×4625
days = 25 days
? The worker worked 25 days in a month.
Q u e s t i o n : 5
A car can cover a distance of 357 km on 42 litres of petrol. How far can it travel on 12 litres of petrol?
S o l u t i o n :
Distance covered by the car with 42 L of petrol = 357 km
Page 2


Q u e s t i o n : 1
If 15 oranges cost Rs 110,  what do 39 oranges cost?
S o l u t i o n :
Cost of 15 oranges = Rs 110
Cost of 1 orange = Rs 
110
15
? Cost of 39 oranges = Rs 
110
15
×39
= Rs 286
Q u e s t i o n : 2
If 8 kg sugar costs Rs 260, how much sugar can be bought for Rs 877.50?
S o l u t i o n :
Amount of sugar bought for Rs 260 = 8 kg
Amount of sugar bought for Re 1 = 
8
260
kg
Now, amount of sugar bought for Rs 877.50 = 
8
260
×877. 50
kg = 27 kg
? 27 kg of sugar can be bought for Rs 877.50.
Q u e s t i o n : 3
The cost of 37 m of silk is Rs 6290. What length of this silk can be purchased for 4420?
S o l u t i o n :
Length of the silk purchased for Rs 6290  = 37 m
Length of the silk purchased for  Re 1= 
37
6290
m
Now, length of the silk purchased for Rs 4,420 = 
37
6290
×4420
m = 26 m
? 26 m of silk can be purchased for Rs 4,420.
Q u e s t i o n : 4
A worker is paid Rs 1110 for 6 days. If his total wages during a month are Rs 4625, for how many days did he work?
S o l u t i o n :
Number of days for which a worker is paid Rs 1,110 = 6
Number of days for which a worker is paid Re 1 = 
6
1110
days
Now, number of days for which a worker is paid Rs 4625=
6
1110
×4625
days = 25 days
? The worker worked 25 days in a month.
Q u e s t i o n : 5
A car can cover a distance of 357 km on 42 litres of petrol. How far can it travel on 12 litres of petrol?
S o l u t i o n :
Distance covered by the car with 42 L of petrol = 357 km
Distance covered by the car with 1 L of petrol = 
357
42
km            
l e s s p e t r o l, l e s s d i s t a n c e
Now, distance covered by the car with 12 L of petrol = 
357
42
×12
= 102 km  
m o r e p e t r o l, m o r e d i s t a n c e
Q u e s t i o n : 6
Travelling 900 km by rail costs Rs 2520. What would be the fare for a journey of 360 km when a person travels by
the same class?
S o l u t i o n :
Cost of travelling 900 km by train = Rs 2520
Cost of travelling 1 km by train = Rs 
2520
900
Now, cost of travelling 360 km by train =Rs 
2520
900
×360
= Rs 1008
? The train fare for a journey of distance 360 km is Rs 1,008.
Q u e s t i o n : 7
A train covers a distance of 51 km in 45 minutes. How long will it take to cover 221 km?
S o l u t i o n :
Time taken to cover a distance of 51 km = 45 min
Time taken to cover a distance of 1 km = 
45
51
min
Time taken to cover distance of 221 km = 
45
51
×221
min = 195 min = 3 h 15 min
? The train will take 3 h 15 min to cover a distance of 221 km.
Q u e s t i o n : 8
If 22.5 metres of a uniform iron rod weighs 85.5 kg, what will be the length of 22.8 kg of the same rod?
S o l u t i o n :
Length of the iron rod that weighs 85.5 kg = 22.5 m
Length of the iron rod that weighs 1 kg = 
22.5
85.5
m              
l e s s w e i g h t, l e s s l e n g t h
? Length of the iron rod that weighs 22.8 kg = 
22.5
85.5
×22. 8 
m = 6 m      
m o r e w e i g h t, m o r e l e n g t h
Page 3


Q u e s t i o n : 1
If 15 oranges cost Rs 110,  what do 39 oranges cost?
S o l u t i o n :
Cost of 15 oranges = Rs 110
Cost of 1 orange = Rs 
110
15
? Cost of 39 oranges = Rs 
110
15
×39
= Rs 286
Q u e s t i o n : 2
If 8 kg sugar costs Rs 260, how much sugar can be bought for Rs 877.50?
S o l u t i o n :
Amount of sugar bought for Rs 260 = 8 kg
Amount of sugar bought for Re 1 = 
8
260
kg
Now, amount of sugar bought for Rs 877.50 = 
8
260
×877. 50
kg = 27 kg
? 27 kg of sugar can be bought for Rs 877.50.
Q u e s t i o n : 3
The cost of 37 m of silk is Rs 6290. What length of this silk can be purchased for 4420?
S o l u t i o n :
Length of the silk purchased for Rs 6290  = 37 m
Length of the silk purchased for  Re 1= 
37
6290
m
Now, length of the silk purchased for Rs 4,420 = 
37
6290
×4420
m = 26 m
? 26 m of silk can be purchased for Rs 4,420.
Q u e s t i o n : 4
A worker is paid Rs 1110 for 6 days. If his total wages during a month are Rs 4625, for how many days did he work?
S o l u t i o n :
Number of days for which a worker is paid Rs 1,110 = 6
Number of days for which a worker is paid Re 1 = 
6
1110
days
Now, number of days for which a worker is paid Rs 4625=
6
1110
×4625
days = 25 days
? The worker worked 25 days in a month.
Q u e s t i o n : 5
A car can cover a distance of 357 km on 42 litres of petrol. How far can it travel on 12 litres of petrol?
S o l u t i o n :
Distance covered by the car with 42 L of petrol = 357 km
Distance covered by the car with 1 L of petrol = 
357
42
km            
l e s s p e t r o l, l e s s d i s t a n c e
Now, distance covered by the car with 12 L of petrol = 
357
42
×12
= 102 km  
m o r e p e t r o l, m o r e d i s t a n c e
Q u e s t i o n : 6
Travelling 900 km by rail costs Rs 2520. What would be the fare for a journey of 360 km when a person travels by
the same class?
S o l u t i o n :
Cost of travelling 900 km by train = Rs 2520
Cost of travelling 1 km by train = Rs 
2520
900
Now, cost of travelling 360 km by train =Rs 
2520
900
×360
= Rs 1008
? The train fare for a journey of distance 360 km is Rs 1,008.
Q u e s t i o n : 7
A train covers a distance of 51 km in 45 minutes. How long will it take to cover 221 km?
S o l u t i o n :
Time taken to cover a distance of 51 km = 45 min
Time taken to cover a distance of 1 km = 
45
51
min
Time taken to cover distance of 221 km = 
45
51
×221
min = 195 min = 3 h 15 min
? The train will take 3 h 15 min to cover a distance of 221 km.
Q u e s t i o n : 8
If 22.5 metres of a uniform iron rod weighs 85.5 kg, what will be the length of 22.8 kg of the same rod?
S o l u t i o n :
Length of the iron rod that weighs 85.5 kg = 22.5 m
Length of the iron rod that weighs 1 kg = 
22.5
85.5
m              
l e s s w e i g h t, l e s s l e n g t h
? Length of the iron rod that weighs 22.8 kg = 
22.5
85.5
×22. 8 
m = 6 m      
m o r e w e i g h t, m o r e l e n g t h
Q u e s t i o n : 9
If the weight of 6 sheets of a paper is 162 grams, how many sheets of the same quality of paper would weigh 13.5
kg?
S o l u t i o n :
Number of paper sheets that weighs 162 g = 6
Number of paper sheets that weighs 1 g = 
6
162
                 
l e s s w e i g h t, l e s s s h e e t s
? Number of paper sheets that weighs 13.5 kg = 
6
162
×13. 5 ×1000
= 500   
m o r e w e i g h t, m o r e s h e e t s
Q u e s t i o n : 1 0
1152 bars of soap can be packed in 8 cartons of the same size. How many such cartons will be required to pack
3888 bars?
S o l u t i o n :
Number of cartons needed to pack 1152 soap bars = 8
Number of cartons needed to pack 1 soap bar = 
8
1152
             
l e s s n u m b e r o f s o a p s, l e s s n u m b e r o f c a r t o n s n e e d e d
 
Now, number of cartons needed to pack 3888 soap bars = 
8
1152
×3888
= 27       
m o r e s o a p s, m o r e c a r t o n n e e d e d
? 27 cartons are needed to pack 3888 soap bars.
Q u e s t i o n : 1 1
If the thickness of a pile of 16 cardboards is 44 mm, how many cardboards will be there in a pile which is 71.5 cm
thick?
S o l u t i o n :
Number of cardboards in a pile of thickness 44 mm = 16
Number of cardboards in a pile of thickness 1 mm = 
16
44
             
Number of cardboards in a pile of thickness 71.5 cm = 
16
44
×71. 5 ×10
= 260        
1 c m = 10 m m
 
? 260 cardboards will be there in a pile of thickness 71.5 cm.
Q u e s t i o n : 1 2
At a particular time of a day, a 7-m-high flagstaff casts a shadow which is 8.2 m long. What is the height of the
building which casts a shadow 20.5 metres in length at the same moment?
Page 4


Q u e s t i o n : 1
If 15 oranges cost Rs 110,  what do 39 oranges cost?
S o l u t i o n :
Cost of 15 oranges = Rs 110
Cost of 1 orange = Rs 
110
15
? Cost of 39 oranges = Rs 
110
15
×39
= Rs 286
Q u e s t i o n : 2
If 8 kg sugar costs Rs 260, how much sugar can be bought for Rs 877.50?
S o l u t i o n :
Amount of sugar bought for Rs 260 = 8 kg
Amount of sugar bought for Re 1 = 
8
260
kg
Now, amount of sugar bought for Rs 877.50 = 
8
260
×877. 50
kg = 27 kg
? 27 kg of sugar can be bought for Rs 877.50.
Q u e s t i o n : 3
The cost of 37 m of silk is Rs 6290. What length of this silk can be purchased for 4420?
S o l u t i o n :
Length of the silk purchased for Rs 6290  = 37 m
Length of the silk purchased for  Re 1= 
37
6290
m
Now, length of the silk purchased for Rs 4,420 = 
37
6290
×4420
m = 26 m
? 26 m of silk can be purchased for Rs 4,420.
Q u e s t i o n : 4
A worker is paid Rs 1110 for 6 days. If his total wages during a month are Rs 4625, for how many days did he work?
S o l u t i o n :
Number of days for which a worker is paid Rs 1,110 = 6
Number of days for which a worker is paid Re 1 = 
6
1110
days
Now, number of days for which a worker is paid Rs 4625=
6
1110
×4625
days = 25 days
? The worker worked 25 days in a month.
Q u e s t i o n : 5
A car can cover a distance of 357 km on 42 litres of petrol. How far can it travel on 12 litres of petrol?
S o l u t i o n :
Distance covered by the car with 42 L of petrol = 357 km
Distance covered by the car with 1 L of petrol = 
357
42
km            
l e s s p e t r o l, l e s s d i s t a n c e
Now, distance covered by the car with 12 L of petrol = 
357
42
×12
= 102 km  
m o r e p e t r o l, m o r e d i s t a n c e
Q u e s t i o n : 6
Travelling 900 km by rail costs Rs 2520. What would be the fare for a journey of 360 km when a person travels by
the same class?
S o l u t i o n :
Cost of travelling 900 km by train = Rs 2520
Cost of travelling 1 km by train = Rs 
2520
900
Now, cost of travelling 360 km by train =Rs 
2520
900
×360
= Rs 1008
? The train fare for a journey of distance 360 km is Rs 1,008.
Q u e s t i o n : 7
A train covers a distance of 51 km in 45 minutes. How long will it take to cover 221 km?
S o l u t i o n :
Time taken to cover a distance of 51 km = 45 min
Time taken to cover a distance of 1 km = 
45
51
min
Time taken to cover distance of 221 km = 
45
51
×221
min = 195 min = 3 h 15 min
? The train will take 3 h 15 min to cover a distance of 221 km.
Q u e s t i o n : 8
If 22.5 metres of a uniform iron rod weighs 85.5 kg, what will be the length of 22.8 kg of the same rod?
S o l u t i o n :
Length of the iron rod that weighs 85.5 kg = 22.5 m
Length of the iron rod that weighs 1 kg = 
22.5
85.5
m              
l e s s w e i g h t, l e s s l e n g t h
? Length of the iron rod that weighs 22.8 kg = 
22.5
85.5
×22. 8 
m = 6 m      
m o r e w e i g h t, m o r e l e n g t h
Q u e s t i o n : 9
If the weight of 6 sheets of a paper is 162 grams, how many sheets of the same quality of paper would weigh 13.5
kg?
S o l u t i o n :
Number of paper sheets that weighs 162 g = 6
Number of paper sheets that weighs 1 g = 
6
162
                 
l e s s w e i g h t, l e s s s h e e t s
? Number of paper sheets that weighs 13.5 kg = 
6
162
×13. 5 ×1000
= 500   
m o r e w e i g h t, m o r e s h e e t s
Q u e s t i o n : 1 0
1152 bars of soap can be packed in 8 cartons of the same size. How many such cartons will be required to pack
3888 bars?
S o l u t i o n :
Number of cartons needed to pack 1152 soap bars = 8
Number of cartons needed to pack 1 soap bar = 
8
1152
             
l e s s n u m b e r o f s o a p s, l e s s n u m b e r o f c a r t o n s n e e d e d
 
Now, number of cartons needed to pack 3888 soap bars = 
8
1152
×3888
= 27       
m o r e s o a p s, m o r e c a r t o n n e e d e d
? 27 cartons are needed to pack 3888 soap bars.
Q u e s t i o n : 1 1
If the thickness of a pile of 16 cardboards is 44 mm, how many cardboards will be there in a pile which is 71.5 cm
thick?
S o l u t i o n :
Number of cardboards in a pile of thickness 44 mm = 16
Number of cardboards in a pile of thickness 1 mm = 
16
44
             
Number of cardboards in a pile of thickness 71.5 cm = 
16
44
×71. 5 ×10
= 260        
1 c m = 10 m m
 
? 260 cardboards will be there in a pile of thickness 71.5 cm.
Q u e s t i o n : 1 2
At a particular time of a day, a 7-m-high flagstaff casts a shadow which is 8.2 m long. What is the height of the
building which casts a shadow 20.5 metres in length at the same moment?
S o l u t i o n :
Height of the flagstaff that casts a shadow of length 8.2 m = 7 m
Height of the building that casts a shadow of length 1 m = 
7
8.2
m                                         
Height of the building that casts a shadow of length 20.5 m = 
7
8.2
×20. 5
m = 17.5 m
? The height of the required building is 17.5 m.
Q u e s t i o n : 1 3
15 men can build a 16.25-m-long wall up to a certain height in one day. How many men should be employed to
build a wall of the same height but of length 26 metres in one day?
S o l u t i o n :
Number of men employed to built the 16.25 m long wall = 15
Number of men required to built a 1 m long wall = 
15
16.25
                       
Number of men that should be employed to built a 26 m long wall = 
15
16.25
×26
= 24
? 24 men should be employed to build a wall of length 26 m in a day.
Q u e s t i o n : 1 4
In a hospital, the monthly consumption of milk of 60 patients is 1350 litres. How many patients can be
accommodated in the hospital if the monthly ration of milk is raised to 1710 litres, assuming that the quota per
head remains the same?
S o l u t i o n :
Number of patients who can consume 1350 L of milk = 60
Number of patients who can consume 1 L of milk = 
60
1350
                                 
Now, number of patients who can consume 1710 L of milk  = 
60
1350
×1710
= 76
Hence, 76 patients can be accommodated in the hospital if the monthly ration of milk is raised to 1710 L.
Q u e s t i o n : 1 5
The extension in an elastic string varies directly as the weight hung on it. If a weight of 150 g produces an
extension of 2.8 cm, what weight would produce an extension of 19.6 cm?
S o l u t i o n :
Weight that would produce an extension of 2.8 cm = 150 g
Weight that would produce an extension of 1 cm = 
150
2.8
g
Weight that would produce an extension of 19.6 cm = 
150
2.8
×
19.6 = 1050 g = 1 kg 50 g           
1 k g = 1000 g
? A weight of 1 kg 50 g would produce an extension of 19.6 cm.
Page 5


Q u e s t i o n : 1
If 15 oranges cost Rs 110,  what do 39 oranges cost?
S o l u t i o n :
Cost of 15 oranges = Rs 110
Cost of 1 orange = Rs 
110
15
? Cost of 39 oranges = Rs 
110
15
×39
= Rs 286
Q u e s t i o n : 2
If 8 kg sugar costs Rs 260, how much sugar can be bought for Rs 877.50?
S o l u t i o n :
Amount of sugar bought for Rs 260 = 8 kg
Amount of sugar bought for Re 1 = 
8
260
kg
Now, amount of sugar bought for Rs 877.50 = 
8
260
×877. 50
kg = 27 kg
? 27 kg of sugar can be bought for Rs 877.50.
Q u e s t i o n : 3
The cost of 37 m of silk is Rs 6290. What length of this silk can be purchased for 4420?
S o l u t i o n :
Length of the silk purchased for Rs 6290  = 37 m
Length of the silk purchased for  Re 1= 
37
6290
m
Now, length of the silk purchased for Rs 4,420 = 
37
6290
×4420
m = 26 m
? 26 m of silk can be purchased for Rs 4,420.
Q u e s t i o n : 4
A worker is paid Rs 1110 for 6 days. If his total wages during a month are Rs 4625, for how many days did he work?
S o l u t i o n :
Number of days for which a worker is paid Rs 1,110 = 6
Number of days for which a worker is paid Re 1 = 
6
1110
days
Now, number of days for which a worker is paid Rs 4625=
6
1110
×4625
days = 25 days
? The worker worked 25 days in a month.
Q u e s t i o n : 5
A car can cover a distance of 357 km on 42 litres of petrol. How far can it travel on 12 litres of petrol?
S o l u t i o n :
Distance covered by the car with 42 L of petrol = 357 km
Distance covered by the car with 1 L of petrol = 
357
42
km            
l e s s p e t r o l, l e s s d i s t a n c e
Now, distance covered by the car with 12 L of petrol = 
357
42
×12
= 102 km  
m o r e p e t r o l, m o r e d i s t a n c e
Q u e s t i o n : 6
Travelling 900 km by rail costs Rs 2520. What would be the fare for a journey of 360 km when a person travels by
the same class?
S o l u t i o n :
Cost of travelling 900 km by train = Rs 2520
Cost of travelling 1 km by train = Rs 
2520
900
Now, cost of travelling 360 km by train =Rs 
2520
900
×360
= Rs 1008
? The train fare for a journey of distance 360 km is Rs 1,008.
Q u e s t i o n : 7
A train covers a distance of 51 km in 45 minutes. How long will it take to cover 221 km?
S o l u t i o n :
Time taken to cover a distance of 51 km = 45 min
Time taken to cover a distance of 1 km = 
45
51
min
Time taken to cover distance of 221 km = 
45
51
×221
min = 195 min = 3 h 15 min
? The train will take 3 h 15 min to cover a distance of 221 km.
Q u e s t i o n : 8
If 22.5 metres of a uniform iron rod weighs 85.5 kg, what will be the length of 22.8 kg of the same rod?
S o l u t i o n :
Length of the iron rod that weighs 85.5 kg = 22.5 m
Length of the iron rod that weighs 1 kg = 
22.5
85.5
m              
l e s s w e i g h t, l e s s l e n g t h
? Length of the iron rod that weighs 22.8 kg = 
22.5
85.5
×22. 8 
m = 6 m      
m o r e w e i g h t, m o r e l e n g t h
Q u e s t i o n : 9
If the weight of 6 sheets of a paper is 162 grams, how many sheets of the same quality of paper would weigh 13.5
kg?
S o l u t i o n :
Number of paper sheets that weighs 162 g = 6
Number of paper sheets that weighs 1 g = 
6
162
                 
l e s s w e i g h t, l e s s s h e e t s
? Number of paper sheets that weighs 13.5 kg = 
6
162
×13. 5 ×1000
= 500   
m o r e w e i g h t, m o r e s h e e t s
Q u e s t i o n : 1 0
1152 bars of soap can be packed in 8 cartons of the same size. How many such cartons will be required to pack
3888 bars?
S o l u t i o n :
Number of cartons needed to pack 1152 soap bars = 8
Number of cartons needed to pack 1 soap bar = 
8
1152
             
l e s s n u m b e r o f s o a p s, l e s s n u m b e r o f c a r t o n s n e e d e d
 
Now, number of cartons needed to pack 3888 soap bars = 
8
1152
×3888
= 27       
m o r e s o a p s, m o r e c a r t o n n e e d e d
? 27 cartons are needed to pack 3888 soap bars.
Q u e s t i o n : 1 1
If the thickness of a pile of 16 cardboards is 44 mm, how many cardboards will be there in a pile which is 71.5 cm
thick?
S o l u t i o n :
Number of cardboards in a pile of thickness 44 mm = 16
Number of cardboards in a pile of thickness 1 mm = 
16
44
             
Number of cardboards in a pile of thickness 71.5 cm = 
16
44
×71. 5 ×10
= 260        
1 c m = 10 m m
 
? 260 cardboards will be there in a pile of thickness 71.5 cm.
Q u e s t i o n : 1 2
At a particular time of a day, a 7-m-high flagstaff casts a shadow which is 8.2 m long. What is the height of the
building which casts a shadow 20.5 metres in length at the same moment?
S o l u t i o n :
Height of the flagstaff that casts a shadow of length 8.2 m = 7 m
Height of the building that casts a shadow of length 1 m = 
7
8.2
m                                         
Height of the building that casts a shadow of length 20.5 m = 
7
8.2
×20. 5
m = 17.5 m
? The height of the required building is 17.5 m.
Q u e s t i o n : 1 3
15 men can build a 16.25-m-long wall up to a certain height in one day. How many men should be employed to
build a wall of the same height but of length 26 metres in one day?
S o l u t i o n :
Number of men employed to built the 16.25 m long wall = 15
Number of men required to built a 1 m long wall = 
15
16.25
                       
Number of men that should be employed to built a 26 m long wall = 
15
16.25
×26
= 24
? 24 men should be employed to build a wall of length 26 m in a day.
Q u e s t i o n : 1 4
In a hospital, the monthly consumption of milk of 60 patients is 1350 litres. How many patients can be
accommodated in the hospital if the monthly ration of milk is raised to 1710 litres, assuming that the quota per
head remains the same?
S o l u t i o n :
Number of patients who can consume 1350 L of milk = 60
Number of patients who can consume 1 L of milk = 
60
1350
                                 
Now, number of patients who can consume 1710 L of milk  = 
60
1350
×1710
= 76
Hence, 76 patients can be accommodated in the hospital if the monthly ration of milk is raised to 1710 L.
Q u e s t i o n : 1 5
The extension in an elastic string varies directly as the weight hung on it. If a weight of 150 g produces an
extension of 2.8 cm, what weight would produce an extension of 19.6 cm?
S o l u t i o n :
Weight that would produce an extension of 2.8 cm = 150 g
Weight that would produce an extension of 1 cm = 
150
2.8
g
Weight that would produce an extension of 19.6 cm = 
150
2.8
×
19.6 = 1050 g = 1 kg 50 g           
1 k g = 1000 g
? A weight of 1 kg 50 g would produce an extension of 19.6 cm.
Q u e s t i o n : 1 6
If 48 men can dig a trench in 14 days, how long will 28 men take to dig a similar trench?
S o l u t i o n :
48 men can dig a trench in 14 days.
1 man can dig the trench in 14 ×
48 days.                                              
l e s s m e n, m o r e d a y s
Therefore, 28 men can dig the trench in 
14×48
28
days = 24 days             
m o r e m e n, l e s s d a y s
Hence, 28 men will take 24 days to dig a similar trench.
Q u e s t i o n : 1 7
16 men can reap a field in 30 days. How many men must be engaged to reap the same field in 24 days?
S o l u t i o n :
No. of men required to reap the field in 30 days = 16
No. of men required to reap the field in 1 day = 16 ×
30                        l e s s d a y s, m o r e m e n
Now, no. of men required to reap the field in 24 days = 
16×30
24
= 20    m o r e d a y s, l e s s m e n
? 20 men are required to reap the field in 24 days.
Q u e s t i o n : 1 8
45 cows can graze a field in 13 days. How many cows will graze the same field in 9 days?
S o l u t i o n :
Number of cows that can graze the field in 13 days = 45
Number of cows that can graze the field in 1 day = 45 ×
13          
L e s s d a y s, m o r e c o w s
Therefore, number of cows that can graze the field in 9 days = 
45×13
9
= 65  
M o r e d a y s, l e s s c o w s
Hence, 65 cows can graze the field in 9 days.
Q u e s t i o n : 1 9
16 horses can consume a certain quantity of corn in 25 days. In how many days would the same quantity be
consumed by 40 horses?
S o l u t i o n :
Time taken by 16 horses to consume the corn = 25 days
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FAQs on RS Aggarwal Solutions: Unitary Method - Mathematics (Maths) Class 7

1. What is the unitary method in mathematics?
Ans. The unitary method is a technique used in mathematics to solve problems that involve ratios or proportions. It involves finding the value of one unit and then using that value to find the value of the given quantity.
2. How can I solve problems using the unitary method?
Ans. To solve problems using the unitary method, first, identify the given quantity and the unit in which it is given. Then, find the value of one unit by dividing the given quantity by the given unit. Finally, use the value of one unit to find the value of the desired quantity.
3. Can the unitary method be used for solving problems in real-life situations?
Ans. Yes, the unitary method can be used to solve various real-life problems. For example, it can be used to find the cost of a single item when the cost of a certain number of items is given, or to find the time taken to complete a task when the time taken to complete a certain part of the task is known.
4. Are there any specific steps to follow while using the unitary method?
Ans. Yes, there are specific steps to follow while using the unitary method. These steps include identifying the given quantity and unit, finding the value of one unit, and finally, using this value to find the value of the desired quantity.
5. Can the unitary method be used for solving problems in higher classes?
Ans. Yes, the unitary method is a fundamental concept in mathematics and can be used to solve problems in higher classes as well. It lays the foundation for solving more complex problems involving ratios and proportions.
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