Two successive discounts, each of x% on the marked price of an article, are equal to a single discount of Rs. 331.20. If the marked price of the article is Rs. 920, then the value of x is:
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 20%
1st discount = x% of 920 = Rs. 9.2x
Have to pay amount Rs. (920 – 9.2x)
2nd discount x% of Rs (920 - 9.2x) = (920 – 9.2x)x/100
Accordingly,
9.2x + x(920 – 9.2x)/100 = 331.20
⇒ 9200x + 9200x – 92x2 = 331200
⇒ 92x2 – 18400x + 331200 = 0
⇒ x2 – 200x + 3600 = 0
⇒ x2 – 180x - 20x + 3600 = 0
⇒ (x – 180)(x – 20) = 0
x = 180 or x = 20
180% invalid as per the question