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

The mean of the 5 observations is \(\frac{x + (x+3) + (x+5) + (x+7) + (x+10)}{5} = \frac{5x + 25}{5} = x + 5 = 9 \implies x = 4\). The last three observations are \(4+5=9\),…

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

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The mean of the 5 observations is x+(x+3)+(x+5)+(x+7)+(x+10)5=5x+255=x+5=9  ⟹  x=4\frac{x + (x+3) + (x+5) + (x+7) + (x+10)}{5} = \frac{5x + 25}{5} = x + 5 = 9 \implies x = 4. The last three observations are 4+5=94+5=9, 4+7=114+7=11, and 4+10=144+10=14, whose mean is 9+11+143=343=1113\frac{9 + 11 + 14}{3} = \frac{34}{3} = 11\frac{1}{3}.

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