1959 AHSME Problems/Problem 13
Problem
The arithmetic mean (average) of a set of numbers is . If two numbers, namely, and , are discarded, the mean of the remaining set of numbers is:
Solution
Since the arithmetic mean of the numbers is , their sum must be . After and are discarded, the sum decreases by , so it must become . But this means that the new mean of the remaining numbers must be . Thusly, our answer is , and we are done.
See also
1959 AHSC (Problems • Answer Key • Resources) | ||
Preceded by Problem 12 |
Followed by Problem 14 | |
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