Correct Answer - Option 3 : 12.5
Given:
The prices of two articles are in the ratio 4 : 5.
If the price of the first article is increased by x% and that of the other is decreased by 30%, then the new prices of A and B will be in the ratio 9 : 7.
Calculation:
Let the prices of two articles be Rs.4p and Rs.5p respectively.
Increased price of first article = (100 + x) × 4p/100
⇒ (100 + x) × p/25
Decreased price of second article = 70 × 5p/100
⇒ 7p/2
According to question,
(100 + x) × p/25 × 2/7p = 9/7
⇒ 200 + 2x = 225
⇒ 2x = 25
⇒ x = 12.5
∴ the correct answer is 12.5%.
