Chapter 9 Direct Proportion and Inverse Proportion Practice Set 37 Solutions

Let the cost of 12 kg onions be Rs x. The quantity of onions and their cost are in direct proportion. ∴ ∴ 7x = 12 × 140 ….(Multiplying both sides by 140x) ∴ x = = 240 We must pay Rs 240 for 12 kg onions.

Let the bunches of feed bought for Rs 1280 be x. The quantity of feed bought and their cost are in direct proportion. ∴ ∴ 600x = 1280 × 15 …. (Multiplying both sides by 15x) ∴ ∴ 32 bunches of feed can be bought for Rs 1280.

Let the food supplement required for 12 cows be x kg. The quantity of food supplement required and the number of cows are in direct proportion. ∴ ∴ ….(13 kg 500 gram = 13.5 kg) ∴ 13.5 × 12 = 9x ….(Multiplying both sides by 9 x 12) ∴ ∴ x = 18 ∴ The food supplement required for 12 cows is 18 kg.

Let the cost of 8 quintals of soyabean be Rs x. The quantity of soyabeans and their cost are in direct proportion. ∴ ∴ 12x = 8 × 36000 ….(Multiplying both sides by 36000x) ∴ ∴ The cost of 8 quintals of soyabean is Rs 24000.

Let the cost of 13 mobiles be Rs x. The quantity of mobiles and their cost are in direct proportion. ∴ ∴ 2x = 13 × 16000 ….(Multiplying both sides by 16000x) ∴ ∴ Rs 104000 will be required to buy 13 mobiles.