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Algebra Difficulty 1.6 Junior Find the answer

The average (mean) of a list of 10 numbers is 17. When one number is removed from the list, the new average is 16. What number was removed?

A number or a short expression. Fractions can be typed as 3/2, and spacing doesn't matter.

Solution

When 10 numbers have an average of 17, their sum is 10×17=17010 \times 17=170. When 9 numbers have an average of 16, their sum is 9×16=1449 \times 16=144. Therefore, the number that was removed was 170−144=26170-144=26.

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