Multiple choice

The average age of A, B and C is 40 years. If the age of B is 9/10 of the average, then what is the average age of A and C?

  1. 38 years

  2. 34 years

  3. 46 years

  4. 42 years
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D Correct answer
Explanation

Sum of ages (A+B+C) = 40 * 3 = 120. B = (9/10) * 40 = 36. A + C = 120 - 36 = 84. Average of A and C = 84 / 2 = 42.

AI explanation

The total age of A, B and C is 3 times 40, which equals 120 years. The age of B is nine tenths of 40, which equals 36 years. Subtract B's age from the total to get the combined age of A and C, which is 120 minus 36, yielding 84 years. Divide this combined age of 84 by 2 to find the average age of A and C, which is 42 years.

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