Concept of “Percentage-08”

Question: When the price of tea was increased by 25%, a family reduced its consumption in such a way that the expenditure on tea was only 20% more than before. If 25 kg were consumed per month before, find the new monthly consumption. [Ans. (a) 24 kg]                       (a) 24 kg (b) 20 kg (c) 28 kg (d) 30 kg (e) none of these

Solution:

Detailed Explanation: 

First Method: Let the initial price of 25 kg of tea is Rs.100.

When the price of tea is increased by 25%, the new price of 25 kg of tea becomes Rs.125.

But, the increase in expenditure is just 20%, so the new expenditure is Rs.120

Rs.125 ≡ 25 kg  

Rs.120 ≡? = 24 kg Ans.

Second Method: When any quantity is changed by x% and y% successively, then the quantity is changed by

[x + y + (xy)/100]%

Or, 25 – x – (25x)/100 = 20

Or, x = 4

So, the decrease in consumption is 4% of 25 kg = 1 kg

New consumption = (25 - 1) kg = 24 kg. Ans.