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  • If the mean of the observations : x, x + 3, x + 5, x + 7, x + 10 is 9, the mean of the last three observations is

If the mean of the observations : x, x + 3, x + 5, x + 7, x + 10 is 9, the mean of the last three observations is

(A)\ 10\frac{1}{3}

(B) \ 10\frac{2}{3}

(C)\ 11\frac{1}{3}

(D)\ 11\frac{2}{3}

Answers (1)

In the given data the mean of the observations x, x + 3, x + 5, x + 7, x + 10 is given as 9

\Rightarrow Mean=\frac{x+x+3+x+5+x+7+x+10}{5}=9

\Rightarrow 5x+25=45

\Rightarrow 5x=45-25

\Rightarrow 5x=20

\Rightarrow x=\frac{20}{5}=4

\therefore Last three observation are

x + 5, x + 7, x + 10

= 4 + 5, 4 + 7, 4 + 10 = 9, 11, 14

\therefore So, the mean of the last three observations

\Rightarrow \frac{9+11+14}{3}=\frac{34}{3}=11\frac{1}{3}

Therefore option (C) is correct.

Posted by

infoexpert23

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