Multiple choice

Eddison owns a shop and sells various items. He sells a carton of Oreo biscuits for \$40 and a carton of Jim-Jam biscuits for \$60. Alfie buys a total of 10 cartons of both Oreo and Jim-Jam biscuits from Eddison's shop, and the average price at which he buys 10 cartons is \$56. However, to reduce the average price, he now plans to buy fewer cartons of Jim-Jam biscuits but the same number of cartons of Oreo biscuits. How many fewer cartons of Jim-Jam biscuits should he buy so that the average price of cartons is \$52?

  1. 3

  2. 4

  3. 5

  4. 6

  5. 7
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Initial cost: 10 cartons, average $56, total $560. Let O be Oreo and J be Jim-Jam. 40O + 60J = 560 and O + J = 10. Solving gives O=2, J=8. New target: average $52 for O + J_new = 10 - x. 40(2) + 60(8-x) = 52(10-x). 80 + 480 - 60x = 520 - 52x. 40 = 8x. x=5.

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