A merchant bought two qualities of rice at the rate of Rs. 120/kg and Rs. 220/kg. In 72 kg of the second quality rice, how much rice (in kg) of the first quality should be mixed so that the resulting mixture may be sold at the rate of Rs. 280/kg to earn a profit of 40%?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 18.
CP per kg = 280 × (100/140) = 200
Let x kg of Rice A mix in the mixture
(120x + 220 × 72)/(x + 72) = 200
⇒ (120x + 15840)/(x + 72) = 200
⇒ 120x + 15840 = 200x + 14400
⇒ 80x = 1440
⇒ x = 18 kg