Rs Aggarwal 2020 2021 Solutions for Class 7 Maths Chapter 9 Unitary Method are provided here with simple step-by-step explanations. These solutions for Unitary Method are extremely popular among Class 7 students for Maths Unitary Method Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Rs Aggarwal 2020 2021 Book of Class 7 Maths Chapter 9 are provided here for you for free. You will also love the ad-free experience on Meritnation’s Rs Aggarwal 2020 2021 Solutions. All Rs Aggarwal 2020 2021 Solutions for class Class 7 Maths are prepared by experts and are 100% accurate.
Page No 133:
Answer:
Cost of 15 oranges = Rs 110
Cost of 1 orange = Rs
∴ Cost of 39 oranges = Rs = Rs 286
Page No 133:
Answer:
Amount of sugar bought for Rs 260 = 8 kg
Amount of sugar bought for Re 1 = kg
Now, amount of sugar bought for Rs 877.50 = kg = 27 kg
∴ 27 kg of sugar can be bought for Rs 877.50.
Page No 133:
Answer:
Length of the silk purchased for Rs 6290 = 37 m
Length of the silk purchased for Re 1= m
Now, length of the silk purchased for Rs 4,420 = m = 26 m
∴ 26 m of silk can be purchased for Rs 4,420.
Page No 133:
Answer:
Number of days for which a worker is paid Rs 1,110 = 6
Number of days for which a worker is paid Re 1 = days
Now, number of days for which a worker is paid Rs 4625= days = 25 days
∴ The worker worked 25 days in a month.
Page No 133:
Answer:
Distance covered by the car with 42 L of petrol = 357 km
Distance covered by the car with 1 L of petrol = km [less petrol, less distance]
Now, distance covered by the car with 12 L of petrol = = 102 km [more petrol, more distance]
Page No 133:
Answer:
Cost of travelling 900 km by train = Rs 2520
Cost of travelling 1 km by train = Rs
Now, cost of travelling 360 km by train =Rs = Rs 1008
∴ The train fare for a journey of distance 360 km is Rs 1,008.
Page No 133:
Answer:
Time taken to cover a distance of 51 km = 45 min
Time taken to cover a distance of 1 km = min
Time taken to cover distance of 221 km = min = 195 min = 3 h 15 min
∴ The train will take 3 h 15 min to cover a distance of 221 km.
Page No 133:
Answer:
Length of the iron rod that weighs 85.5 kg = 22.5 m
Length of the iron rod that weighs 1 kg = m [less weight, less length]
∴ Length of the iron rod that weighs 22.8 kg = m = 6 m [more weight, more length]
Page No 133:
Answer:
Number of paper sheets that weighs 162 g = 6
Number of paper sheets that weighs 1 g = [less weight, less sheets]
∴ Number of paper sheets that weighs 13.5 kg = = 500 [more weight, more sheets]
Page No 133:
Answer:
Number of cartons needed to pack 1152 soap bars = 8
Number of cartons needed to pack 1 soap bar = [less number of soaps, less number of cartons needed]
Now, number of cartons needed to pack 3888 soap bars = = 27 [more soaps, more carton needed]
∴ 27 cartons are needed to pack 3888 soap bars.
Page No 133:
Answer:
Number of cardboards in a pile of thickness 44 mm = 16
Number of cardboards in a pile of thickness 1 mm =
Number of cardboards in a pile of thickness 71.5 cm = = 260 [1 cm=10 mm]
∴ 260 cardboards will be there in a pile of thickness 71.5 cm.
Page No 133:
Answer:
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 = m
Height of the building that casts a shadow of length 20.5 m = m = 17.5 m
∴ The height of the required building is 17.5 m.
Page No 133:
Answer:
Number of men employed to built the 16.25 m long wall = 15
Number of men required to built a 1 m long wall =
Number of men that should be employed to built a 26 m long wall = = 24
∴ 24 men should be employed to build a wall of length 26 m in a day.
Page No 133:
Answer:
Number of patients who can consume 1350 L of milk = 60
Number of patients who can consume 1 L of milk =
Now, number of patients who can consume 1710 L of milk = = 76
Hence, 76 patients can be accommodated in the hospital if the monthly ration of milk is raised to 1710 L.
Page No 133:
Answer:
Weight that would produce an extension of 2.8 cm = 150 g
Weight that would produce an extension of 1 cm = g
Weight that would produce an extension of 19.6 cm = 19.6 = 1050 g = 1 kg 50 g [1 kg = 1000 g]
∴ A weight of 1 kg 50 g would produce an extension of 19.6 cm.
Page No 134:
Answer:
48 men can dig a trench in 14 days.
1 man can dig the trench in 14 48 days. [less men, more days]
Therefore, 28 men can dig the trench in days = 24 days [more men, less days]
Hence, 28 men will take 24 days to dig a similar trench.
Page No 134:
Answer:
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 (less days, more men)
Now, no. of men required to reap the field in 24 days = = 20 (more days, less men)
∴ 20 men are required to reap the field in 24 days.
Page No 135:
Answer:
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 [Less days, more cows]
Therefore, number of cows that can graze the field in 9 days = = 65 [More days, less cows]
Hence, 65 cows can graze the field in 9 days.
Page No 135:
Answer:
Time taken by 16 horses to consume the corn = 25 days
Time taken by 1 horse to consume the corn = 2516 [less horses, more time taken]
Time taken by 40 horses to consume the corn = = 10 days [more horses, less time taken]
Hence, 40 horses would consume the same quantity of corn in 10 days.
Page No 135:
Answer:
Days taken to finish the book if 18 pages are read everyday = 25
Days taken to finish the book if 1 page is read everyday = 18 25 [less pages, more days]
Now, days taken to finish the book if 15 pages are read everyday = = 30 [more pages, less days]
Hence, the girl will take 30 days to finish the book if she reads 15 pages everyday.
Page No 135:
Answer:
Time taken to type 40 words per minute = 24 min
Time taken to type a word per minute = 2440 min
Now, time taken to type 48 words per minute = = 20 min
Hence, Geeta will take 20 minutes to type the same document if her typing speed is 48 words/min.
Page No 135:
Answer:
Time taken to cover the distance at a speed of 45 km/h = 3 h 20 min = 200 min
Time taken to cover the distance at a speed of 1 km/h = 45 3.33 min [less speed, more time]
Time taken to cover the distance at a speed of 36 km/h = = 4.1625 h ≈ 4 h 10 min
Hence, the bus will take 4 h 10 min to cover the distance if its speed is 36 km/h.
Page No 135:
Answer:
Time taken to make 240 tonnes of steel = 30 days
Time taken to make 1 tonne of steel = 30 240 days
Now, time taken to make 300 or (240 + 60) tonnes of steel = = 24 days
∴ The materials will last for 24 days if 60 more tonnes of steel is to be made that month.
Page No 135:
Answer:
Initially, the contractor had 210 men for 60 days. After 12 days, 70 more men joined.
210 men can finish the work in 48 days
1 man can finish the work in 21048 days
Now, 280 men can finish the work in days = 36 days.
Hence, it will take 36 days to finish the remaining work.
Page No 135:
Answer:
No. of men for which the provision will last for 25 days = 360
No. of men for which the provision will last for 1 day = 360 25
Now, no. of men for which the provision will last for 30 days = = 300
∴ 60 men, i.e., (360 − 300), must be transferred to another camp so that the provision lasts for 30 days.
Page No 135:
Answer:
Number of days for which the food is sufficient for 120 men = 195
Number of days for which food is sufficient for 1 man = 120195
Number of days for which food is sufficient for 90 men = = 260
Hence, the food will last for 260 days.
Page No 135:
Answer:
We are given that in a fort, 1200 soldiers had enough food for 28 days.
Let x soldiers left after 4 days, thus, remaining soldiers = 1200 - x
Now, for these remaining soldiers food lasts for 32 days.
As number of soldiers decrease, food lasts long.
Thus, situation after 4 days is
Thus, 300 soldiers left the fort after 4 days.
Page No 135:
Answer:
(c) 45.6 kg
Weight of the rod of length 4.5 m = 17.1 kg
Weight of the rod of length 1 m = kg [less length, less weight]
∴ Weight of the rod of length 12 m = = 45.6 kg [more length, more weight]
Page No 135:
Answer:
(d) none of these
0.8 cm represents 8.8 km.
1 cm represents km.
80.5 cm represents = 885.5 km.
Page No 135:
Answer:
Distance covered in 20 min = 5 km
Distance covered in 1 min = km [less time, less distance covered]
Distance covered in 50 min = = 12.5 km [more time, more distance covered]
Hence, Raghu will cover a distance of 12.5 km in 50 minutes.
Thus, the correct option is (c).
Page No 135:
Answer:
Number of days for which 500 men have enough food = 24
Number of days for which 1 man has enough food = 24 500 [less men, more food]
Number of days for which 800 men have enough food = = 15 [more men, less food]
Hence, the food will last for 15 days after the reinforcement of 300 men.
Thus, the correct option is (d).
Page No 135:
Answer:
Time taken to fill 1
Time taken to fill of a cistern = min = 15 seconds
Hence, it will take 15 seconds to fill the rest of the cistern.
Thus, the correct option is (b).
Page No 136:
Answer:
Number of cows that eat as much as 15 buffaloes = 21
Number of cows that eat as much as 1 Buffalo =
Number of cows that eat as much as 35 buffaloes = = 49
Hence, 49 cows will eat as much as 35 buffaloes.
Thus, the correct option is (a).
Page No 136:
Answer:
(b) 75 m
Height of the tree that casts a 4 m long shadow = 6 m
Height of the tree that casts a 1 m long shadow = m
∴ Height of the flag pole that casts a 50 m long shadow = = 75 m
Page No 136:
Answer:
8 men finish the work in 40 days.
1 man can finish the work in 840 days. [Less men, more days]
10 men can finish the work in = 32 days. [More men, less days]
∴ If 2 more men join them, the work will be completed in 32 days.
The correct option is (b).
Page No 136:
Answer:
Number of days taken to reap the field by 16 men = 30 days
Number of days taken to reap the field by 1 man = 3016 days [Less men, more days]
Number of days taken to reap the field by 20 men = = 24 days [More men, less days]
Hence, 20 men will take 24 days to reap the field.
The correct option is (b).
Page No 136:
Answer:
Time taken to fill the tank by 10 pipes = 24 min
Time taken to fill the tank by 1 pipe = 24 10 min [Less pipes, more time taken]
Time taken to fill the tank by 8 pipes = min = 30 min [More pipes, less time taken]
Hence, it will take 30 minutes to fill the tank if two pipes go out of order.
The correct option is (c).
Page No 136:
Answer:
Cost of 72 eggs = Rs 108
Cost of 1 egg = Rs
Cost of 132 eggs = RS = Rs 198
Hence, 132 eggs will cost Rs 198.
The correct option is (d).
Page No 136:
Answer:
Time taken by 12 workers to complete the job = 4 h
Time taken by 1 worker to complete the job = h
Time taken by 15 workers to complete the job = = 3 h 12 min
Hence, 15 workers will complete the job in 3 h 12 min.
The correct option is (b).
Page No 136:
Answer:
500 men had enough food for 24 days.
1 man had enough food for 24500 days. [Less men, more days]
800 men had enough food for = 15 days [More men , less days]
Hence, the food will now last for 15 days after the reinforcement of 300 men.
The correct option is (a).
Page No 136:
Answer:
(c) 98
No. of rounds around the cylinder of radius 14 cm = 140
No. of rounds around the cylinder of radius 1 cm = [Less radius, more rounds]
No. of rounds around the cylinder of radius 20 cm = = 98 [More radius, less rounds]
Hence, the rope makes 98 rounds around the circumference of the cylinder of radius 20 cm.
Page No 136:
Answer:
No. of toys made in h = 1
No. of toys made in 1 h =
No. of toys made in h =
Hence, the worker will make 11 toys in h.
The correct option is (d).
Page No 136:
Answer:
Men required to finish the work in 8 days = 10
Men required to finish the work in 1 day = 108 [More day, less men]
Men required to finish the work in half a day = = 160 [Less days, more men]
Hence, 150 (i.e., 160 − 10) men are added to finish the work in half a day.
The correct option is (d).
Page No 137:
Answer:
Cost of 8 toys = Rs 192
Cost of 1 toy = Rs = Rs 24
∴ Cost of 14 toys = = Rs 336
Page No 137:
Answer:
Distance covered with 15 L of petrol= 270 km
Distance covered with 1 L of petrol = km
Distance covered with 8 L of petrol= km = 144 km
Page No 137:
Answer:
Cost of 15 envelopes = Rs 11.25
Cost of 1 envelope = Rs
∴ Cost of 20 envelopes = = Rs 15
Page No 137:
Answer:
Number of cows that graze the field in 20 days = 24
Number of cows that graze the field in 1 day = 2420 [Less days, more cows]
∴ Number of cows that graze the field in 15 days = = 32 cows [More days, less cows]
Page No 137:
Answer:
Time taken to finish the work by 8 men = 15 h
Time taken to finish the work by 1 man = 815 h [Less men, more time taken]
∴ Time taken to finish the work by 20 men = h = 6 h [More men, less time taken]
Page No 137:
Answer:
Time taken to fill of the cistern = 1 min
Time taken to fill 1 cistern = = 1.25 min = 1 min 15 sec
Hence, it will take 1 min 15 sec to fill the empty cistern.
Page No 137:
Answer:
Time taken to cover the distance at a speed of 45 km/h = 3 h 20 min
Time taken to cover the distance at a speed of 1 km/h = 45 3.33 h [Less speed, more time taken]
(20 min = 0.33 hour)
∴ Time taken to cover the distance at a speed of 50 km/h = h ≈ 3 h [More speed, less time taken]
Page No 137:
Answer:
Number of days with enough food for 120 men = 30
Number of days with enough food for 1 man = [Less men, more days]
∴ Number of days with enough food for 100 men = = 36 [More men, less days]
Page No 137:
Answer:
(c) 644 km
1 cm represents 8 km.
∴ 80.5 cm represents = 644 km.
Page No 137:
Answer:
(a) 24 days
16 men can reap the field in 30 days.
1 man can reap the field in 3016 days. [Less men, more days]
∴ 20 men can reap the field in = 24 days [More men, less days]
Page No 137:
Answer:
(b) 49
Number of cows that eat as much as 15 buffaloes = 21
Number of cows that eat as much as 1 buffalo =
∴ Number of cows that eat as much as 35 buffaloes = = 49
Page No 137:
Answer:
Number of cows that graze the field in 12 days = 45
Number of cows that graze the field in 1 day =
∴ Number of cows that graze the field in 9 days = = 60
Page No 137:
Answer:
(b) Rs 162
Cost of 72 eggs = Rs 108
Cost of 1 egg =Rs
Cost of 108 eggs = Rs = Rs 162
Page No 137:
Answer:
(i) 588 days
42 men can dig the trench in 14 days.
1 man can dig the trench in 14 42 days = 588 days
(ii) Rs. 48
15 oranges cost Rs 60.
12 oranges will cost Rs = Rs 48
(iii) 10.8 kg
A rod of length 10 m weighs 18 kg.
A rod of length 6 m will weigh = 10.8 kg
(iv) 3 h 12 min
12 workers finish the work in 4 h.
15 workers will finish the work in = 3.2 h = 3 h 12 min
Page No 137:
Answer:
(i) F
10 pipes fill the tank in 24 min.
1 pipe will fill the tank in 24 10 min. (Less pipes, more time taken)
8 pipes will fill the tank in = 30 min (More pipes, less time taken)
(ii) T
8 men finish the work in 40 days.
1 man finishes the work in 840 days. (Less men, more days taken)
10 men will finish the work in = 32 days (More men, less days taken)
(iii) T
A 6 m tall tree casts a shadow of length 4 m.
A 1 m tall tree cast a shadow of length m.
A 75 m tall pole will cast a shadow of length =50 m
(iv) T
1 toy is made in h. (Less toys, less time taken)
12 toys can be made in = 8 h (More toys, more time taken)
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