42 is the arithmetic mean of a group of 30 memebers. If two numbers, 82 and 44, are removed, then find the arithmetic mean of the remaining numbers.
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Since 42 is the mean, it was calculated by taking:
mean = sum / # of items
Substituting:
42 = sum / 30
Therefore the sum is 30 * 42 = 1260
If you subtract 82 and 44 from this, you get:
1260 - 82 - 44 = 1134
This is now the sum of 28 items, so the new mean is:
1134/28 = 40.5
Hope that helps...
Steve
