If price of grains is increased by 50%, by how much percent a person has to decrease his consumption of grains so that expenditure on grain increases only by 17%.
Sol. Let the original price of grain be Rs.100 per kg. and original consumption be 100 kg. original expenditure = 100 x 100 = Rs. 10,000 New price = Rs.150 per kg & new expenditure must be Rs. 10,000 New expenditure = new price x new consumption ⇒ 11700 = 150 x new consumption ⇒ new consumption = 11700/150= 78 kg. Decrease in consumption = 100 – 78 = 22 kg. % decrease in consumption = 22 %