Statisticshard · Past Paper
If the mean of 5 observations $x, x+2, x+4, x+6, x+8$ is 11, then the mean of first three observations is:
A9
B11
C7
D8
✓ Correct Answer: A — 9
Mean of $x, x+2...x+8$ is $x+4$. $x+4=11 \Rightarrow x=7$. First three are 7, 9, 11. Mean = 9.
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