Multiple choice

The average of 27 numbers is 60. If one number is changed from 28 to 82, the average is

  1. $56$
  2. $58$
  3. $62$
  4. $64$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The average of 27 numbers is 60, so their sum is 27 × 60 = 1620. When one number changes from 28 to 82, the sum increases by (82 - 28) = 54. The new sum is 1620 + 54 = 1674. The new average is 1674 ÷ 27 = 62. Alternatively, the net change per number is 54/27 = 2, so the average increases by 2: 60 + 2 = 62.

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