Question

The mean of seven numbers is 12.0. When one new number is added, the average of new numbers becomes 12.5. What is the new number?

Answer 1

Mean of the 7 numbers = 12.0
Total of the 7 numbers = 12.0 x 7 = 84

Mean of the 8 numbers = 12.5
Total of the 8 numbers = 12.5 x 8 = 100

The 8th number is 100 - 84 = 16

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Answer: The new number is 16.
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