ISEE Mathematics Achievement Question 25: Answer and Explanation

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Question: 25

11. Aluminum bronze consists of copper and aluminum, usually in the ratio of 10:1 by weight. If an object made of this alloy weighs 77 pounds, how many pounds of aluminum does it contain

  • A. 7
  • B. 7.7
  • C. 10
  • D. 70

Correct Answer: A

Explanation:

The correct answer is (A). Copper and aluminum in the ratio of 10:1 means 10 parts copper to 1 part aluminum.

Let x = weight of aluminum

Then 10x = weight of copper

10x + x = 77

11x = 77

x = 7

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