Read RD Sharma Solutions Class 7 Chapter 10 Unitary Method below, students should study RD Sharma class 7 Mathematics available on Studiestoday.com with solved questions and answers. These chapter wise answers for class 7 Mathematics have been prepared by teacher of Grade 7. These RD Sharma class 7 Solutions have been designed as per the latest NCERT syllabus for class 7 and if practiced thoroughly can help you to score good marks in standard 7 Mathematics class tests and examinations
Exercise 10.1
Question 1: 20 chocolates cost Rs 320. Find the cost of 35 such chocolates.
Solution 1:
The 20 chocolates cost are Rs 320
Cost of one chocolate is 320/20
Thus, the 35 chocolate’s cost are
= 320/20 × 35
= Rs 560
So, the cost of 35 chocolates is 560
Question 2: The cost of 40 meters of cloth is Rs 200. Find the cost of 50 meters of cloth.
Solution 2:
The 40 meters cloth’s cost are Rs 200
Cost of the one-meter cloth is 200/40
Thus, 50-meter cloth cost are 200/40 × 50
= Rs 250
So, the cost of 50 meters of cloth is Rs. 250
Question 3: A car can cover a distance of 522 km on 36 liters of petrol. How far can it travel on 14 liters of petrol?
Solution 3:
The number of kilometers a car can cover using 36 liters of petrol is 522 km
Number of kilometers a car can cover using one liter of petrol is 522/36
So, the number of kilometers a car can cover by using 14 liters
= 522/36 × 14
= 203 km
So, the car cover 203 km in 14 liters of petrol
Question 4: Travelling 900 km by rail costs Rs 280. What would be the fare for a journey of 360 km when a person travels by the same class?
Solution 4:
The cost of travelling 900 km by rail is Rs 280
Thus, cost of travelling one km by rail is 280/900
Hence, Cost of travelling 360 km by rail is
= 280/900 × 360
= Rs 112
So, fare for a journey Rs. 112 of 360 km.
Question 5: If 6 oil tankers can be filled by a pipe in 4(1/2) hours, how long does the pipe take to fill 4 such oil tankers?
Solution 5:
The time taken by 6 oil tankers to be filled by a pipe = 4 (1/2) hours
= (9/2) hours
Time taken by a oil tanker to be filled by a pipe = ((9/2))/6 hours
= 9/((2 x 6)) = 9/12 hours
Hence time taken by 4 oil tankers to be filled by a pipe = 9/12 × 4
= 3 hours
So, the 4 oil tankers filled in 3 hours.
Question 6: 3/4 of the salary per month is Rs 600. What is the salary per month?
Solution 6:
3/4 of the salary per month = 600
Let x be the salary of the month
Thus 3/4 × x = 600
= x = 600 × 4/3
= x = 800
Thus, salary per month is Rs 800
Question 7: The cost of 32 tables is Rs 23520. Find the number of such tables that can be purchased for Rs 51450.
Solution 7:
The number of tables bought for Rs. 23520 = 32 tables
Number of tables bought for Rs 1 = 32/23520
So, number of tables bought for Rs 51450
= 32/23520 × 51450 = 70
So, in the Rs. 51450, 70 tables can be purchased.
Question 8: The yield of wheat from 6 hectares is 280 quintals. Find the number of hectares required for a yield of 225 quintals.
Solution 8:
The number of hectares for a yield of 280 quintals is 6 hectares
Number of hectares required for a yield of 1 quintal is 6/280 hectares
Hence, the number of hectares required for a yield of 225 quintals =6/280× 225
= 4 23/28 hectares
So, in the 4 23/28 hectares required for a yield of 225 quintals.
Question 9: Fifteen post cards cost Rs 2.25. What will be the cost of 36 post cards? How many postcards can we buy in Rs 45?
Solution 9:
The Cost of 15 post cards is Rs 2.25
Cost of one post card is 2.25/15
Hence, the cost of 36 post cards is 2.25/15 × 36
= Rs 5.40
Number of post cards bought for Rs 2.25 = 15
Numbers of post cards bought for Rs 1 = 15/2.25
Hence number of post cards bought for Rs 45 = 15/2.25 × 45
= 300
So, 300 postcards can buy in Rs. 45.
Question 10: A rail journey of 75 km costs Rs 215. How much will a journey of 120 km cost?
Solution 10:
Cost of a rail journey of 75 km = Rs 215
Cost of a rail journey of one km = 215/75
Hence, cost of a rail journey of 120 km = 215/75 × 120
= Rs 344
So, Rs. 344 will fare of a journey of 120 km.
Question 11: If the sales tax on a purchase worth Rs 60 is Rs 4.20. What will be the sales tax on the purchase worth of Rs 150?
Solution 11:
The sales tax on the purchase worth of Rs 60 = Rs 4.20
Sales tax on the purchase worth of Rs 1 = Rs 4.2060
=Rs 150 = 4.20/60 × 150
= Rs 10.50
Hence, sales tax on the purchase worth of Rs. 150 is Rs. 10.50
Question 12: 52 packets of 12 pencils each, cost Rs 499.20. Find the cost of 65 packets of 10 pencils each.
Solution 12:
The total number of pencils in 52 packets of 12 pencils each = 52 × 12
= 624 pencils
that cost of 624 pencils = Rs 499.20
Cost of one pencil = 499.20/624
Number of pencils in 65 packets of 10 pencils each = 65 x 10
= 650 pencils
Therefore, cost of 650 pencils = 499.20/624 × 650
= Rs 520.
So, the cost od 650 pencils is Rs. 520.