Statisticshard · Past Paper
If the mean of 10 observations is 15, and 2 is added to each of first 5 and 4 is added to each of last 5, the new mean is:
A18
B21
C17
D19
✓ Correct Answer: A — 18
Total increase = (5*2) + (5*4) = 10 + 20 = 30. Increase in mean = 30/10 = 3. New mean = 15 + 3 = 18.
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