Question

If the price of coffee decreased by 20% then by how much percentage must a house wife increase her consumption to have no extra expenditure?

1. 40%
2. 20%
3. 15%
4. 50%
5. None of these

Answer 1

Correct Answer - Option 5 : None of these

Given:

Coffee price decreased by = 20%

Expenditure not to be increased

Calculation:

Let, Price of per kg coffee = Rs.10x

Let, Total purchase capacity initially = 10y kg

Total expenditure = (10x) × (10y) = Rs.100xy

New price after reduction = {(100 – 20)/100} × 10x = Rs.8x

Let, a kg more coffee consume in same expenditure after price reduction

Final purchase capacity after reduction = (10y + a) kg

As question says,

(8x) × (10y + a) = 100xy

⇒ a = 2.5y

Consumption percentage increase = (2.5xy/10y) × 100 = 25%

∴ 25% of consumption increased after decreasing price with no extra expenditure.