Multiple choice

The average of five numbers is 47. If one number is excluded, then the average becomes 45. The excluded number is

  1. 45

  2. 47

  3. 50

  4. 55
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D Correct answer
Explanation

Sum of 5 numbers = 5 × 47 = 235. Excluding one number, average becomes 45, so sum of 4 numbers = 4 × 45 = 180. Excluded number = 235 - 180 = 55. This uses the basic average formula: average = sum/n.

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