The price of a product is decreased by x% and then increased by x%. The final price becomes 10% less than the original. What is the value of x (approximately)?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 31.6.
Let original price = 100
Final price = 100 × (1 – x/100)(1 + x/100) = 100(1 – x2/10000)
100(1 – x2/10000) = 90
⇒ 1 – x2/10000 = 0.9
⇒ x2/10000 = 0.1
⇒ x2 = 1000
⇒ x ≈ 31.6