Statisticshard · Past Paper
If the mean of first $n$ natural numbers is $3n/5$, then $n$ is:
A4
B5
C6
D7
✓ Correct Answer: A — 4
$(n+1)/2 = 3n/5 \Rightarrow 5n + 5 = 6n \Rightarrow n = 5$. Wait, let me recheck. $(5+1)/2 = 3$. $3(5)/5 = 3$. Yes, n=5.
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