Ratio Proportion
Chapter 12
Exercise 12.3
EX 12.3 QUESTION 1.
If the cost of 7 m of cloth is ₹ 1470, find the cost of 5 m of cloth.
Solution:
Cost of 7 m cloth = ₹ 1470
Cost of 1 m cloth = 1470 / 7 = ₹ 210
So, cost of 5 cloth = 210 × 5 = 1050
∴ Cost of 5 m cloth = ₹ 1050
EX 12.3 QUESTION 2.
Ekta earns ₹ 3000 in 10 days. How much will she earn in 30 days?
Solution:
Earning of 10 days = ₹ 3000
Earning of 1 day = 3000 / 10 = ₹ 300
Earning of 30 days == 300 × 30
= ₹ 9000
EX 12.3 QUESTION 3.
If it has rained 276 mm in the last 3 days, how many cm of rain will fall in one full week (7 days)? Assume that the rain continues to fall at the same rate.
Solutions:
Rain in 3 days = 276 mm
Rain in one day = 276 / 3
= 92 mm
Rain in 7 days = 92 × 7
= 644 mm
EX 12.3 QUESTION 4.
Cost of 5 kg of wheat is ₹ 91.50.
(a) What will be the cost of 8 kg of wheat?
(b) What quantity of wheat can be purchased in ₹ 183?
Solution:
Cost of 5 kg wheat = ₹ 91.50.
Cost of 1 kg wheat = 91.50 / 5 = ₹ 18.3
Cost of 8 kg wheat = 18.3 × 8 = ₹ 146.40
(b) Wheat purchased in ₹ 91.50 = 5 kg
Wheat purchased in ₹ 1 = 5 / 91.50 kg
wheat purchased in ₹ 183 = (5 / 91.50) × 183
= 10 kg
EX 12.3 QUESTION 5.
The temperature dropped 15 degree celsius in the last 30 days. If the rate of temperature drop remains the same, how many degrees will the temperature drop in the next ten days?
Solutions:
Temperature drop in 30 days = 150 C
Temperature drop in 1 day = 15 / 30 = (1 / 2)0 C
Temperature drop in next 10 days = (1 / 2) × 10
= 50 C
EX 12.3 QUESTION 6.
Shaina pays ₹ 15000 as rent for 3 months. How much does she has to pay for a whole year, if the rent per month remains same?
Solution:
Rent paid for 3 months = ₹ 15000
Rent paid for 1 month = 15000 / 3 = ₹ 5000
Rent paid for 12 months = 5000 × 12
= ₹ 60,000
EX 12.3 QUESTION 7.
Cost of 4 dozen bananas is ₹ 180. How many bananas can be purchased for ₹ 90?
Solution:
Cost of 4 dozen bananas = ₹ 180
Cost of 48 bananas = ₹ 180 [4 dozen = 4 x 12 = 48]
From ₹ 180, the number of bananas can be purchased = 48
From ₹ 1, the number of bananas can be purchased = 48 / 180 = 4 /15
From ₹ 90, the number of bananas can be purchased = (4 / 15) x 90 = 24 bananas.
EX 12.3 QUESTION 8.
The weight of 72 books is 9 kg. What is the weight of 40 such books?
Solution:
Weight of 72 books = 9 kg
Weight of 1 book = 9 / 72 = 1 / 8 kg
So, weight of 40 books = (1 / 8) × 40 = 5 kg
EX 12.3 QUESTION 9.
A truck requires 108 litres of diesel for covering a distance of 594 km. How much diesel will be required by the truck to cover a distance of 1650 km?
Solution:
Diesel required for covering 594 km = 108 litres
Diesel required for covering 1 km = 108 / 594 = 2 / 11 litre
So, diesel required for covering 1650 km = (2 / 11) × 1650
= 300 litres
EX 12.3 QUESTION 10.
Raju purchases 10 pens for ₹ 150 and Manish buys 7 pens for ₹ 84. Can you say who got the pens cheaper?
Solution:
Raju purchase 10 pens for = 10 pens
Raju purchase 1 pen for = 150 / 10 = ₹ 15
Manish Raju purchase 10 pens for = ₹ 84
Manish purchase 1 pen for = 84 / 7 = ₹ 12
EX 12.3 QUESTION 10.
Anish made 42 runs in 6 overs and Anup made 63 runs in 7 overs. Who made more runs per over?
Solutions:
Anish made in 6 overs = 42 runs
Anish made in 1 over = 42 / 6= 7
Anup made in 7 overs = 63
Anup made in 1 over = 63 / 7
= 9
