Exercise 10.1
1. 20 chocolates cost Rs 320. Find the cost of 35 such chocolates.
Solution:
2. The cost of 40 meters of cloth is Rs 200. Find the cost of 50 meters of cloth.
Solution:
Cost of 40 meters of cloth = Rs 200
Cost of 1 meter of cloth = Rs (200/40)
Therefore, the cost of 50 chocolates = Rs ((200/40) × 50) = Rs 250
3. A car can cover a distance of 522 km on 36 liters of petrol. How far can it travel on 14 litres of petrol?
Solution:
Given that number of kilometres a car can cover by using 36 litres of petrol = 522 km
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:
It is given that,
Travelling 900 km rail costs Rs. 280
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:
Given that time taken by 6 oil tankers to be filled by a pipe = 4 (1/2) hours = (9/2) hours
Time taken by 1 oil tankers to be filled by a pipe = (9/2)/6 hours
Hence time taken by 4 oil tankers to be filled by a pipe = (9/2)/6 × 4
= (9/12) × 4
= 3 hours
6. 3/4 of the salary per month is Rs 600. What is the salary per month?
Solution:
Let the salary be ‘x’
Given,
X = Rs 800
Therefore, the salary per month is Rs 800
7. The cost of 32 tables is Rs 23520. Find the number of such tables that can be purchased for Rs 51450.
Solution:
Given that number of tables bought for Rs 23520 = 32
8. The yield of wheat from 6 hectares is 280 quintals. Find the number of hectares required for a yield of 225 quintals.
Solution:
Number of hectares required for a yield of 280 quintals = 6 hectares
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:
Given cost of 15 post cards = Rs 2.25
Cost of 1 post card is = 2.25/15
Hence, the cost of 36 post cards = (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 for Rs 45 = (15/2.25) × 45
= 300
10. A rail journey of 75 km costs Rs 215. How much will a journey of 120 km cost?
Solution:
Given cost of a rail journey of 75 km = Rs 215
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:
Sales tax on the purchase worth of Rs 60 = Rs 4.20
12. 52 packets of 12 pencils each, cost Rs 499.20. Find the cost of 65 packets of 10 pencils each.
Solution:
Total number of pencils in 52 packets of 12 pencils each = 52 × 12 = 624
Cost of 624 pencils = Rs 499.20