Math Revision ch-Ratio, Proportion and Unitary Method
Extra Questions for Practice
1) Find the ratio of the following:
(a) 56 to 63.
(b) 55 to 120.
2)Ramesh deposited ₹ 2050 in a bank and in the month of January he withd_rew ₹ 410 from his account on the last date of the month. Find the ratio of
(a) Money withdrawn to the total money deposited.
(b) Money withdrawn to the remaining amount in the bank.
3) There are 180 students in a class. Number of girls are 75. Find the ratio of the girls to the number of boys.
4) Green paint is made by mixing blue, yellow and white paints in the ratio 2 : 7 : 1. How much blue paint is needed to make 64 litres of green paint?
5) Are 20, 25, 12, 15 in proportion?
6) The first, second and fourth terms in a proportion are 32, 112, 217 respectively. Find the third term.
Solution:1
Solution: 2
Total money deposited = ₹ 2050
Amount of money withdrawn = ₹ 410
Amount of money left in the bank = ₹ 2050 – ₹ 410 = ₹ 1640
(a) Ratio of money withdrawn to the total money deposited
∴ Required ratio = 1 : 5
(b) Ratio of money withdrawn to the money left in the bank
∴ Required ratio = 1 : 4
Solution: 3
Total number of students = 180
Number of girls = 75
Number of boys = 180 – 75 = 105
∴ Ratio of number of girls to the number of boys
Required ratio = 5 : 7
Solution: 4
Here, sum of ratios = 2 + 7 + 1 = 10
∴ Total quantity of green paint = 64 litres
Quantity of blue paint =
Therefore, the required blue paint = 12.8 litres.
Solution: 5
We have 20, 25, 12, 15
Product of extremes = 20 x 15 = 300
Product of middles = 25 x 12 = 300
Since both the products are same.
∴ The four numbers 20, 25, 12, 15 are in proportion.
Solution: 6
Let the third term be x.
∴ 32, 112, x and 217 are in proportion.
∴ 32 : 112 :: x : 217
Thus, the third term = 62.
