Statisticsmedium · Past Paper
A set of data consists of 10 items with mean 12. If another 10 items with mean 18 are added, what is the new mean?
A12
B15
C18
D30
✓ Correct Answer: B — 15
Combined mean = (10*12 + 10*18) / 20 = (120 + 180) / 20 = 300 / 20 = 15.
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