If the mean of the data 7, 8, 9, 7, 8, 7, lam | vedclass

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(D) Given the mean of the data $7, 8, 9, 7, 8, 7, \lambda, 8$ is $8$.Mean $= \frac{7+8+9+7+8+7+\lambda+8}{8} = 8$$\Rightarrow \frac{54+\lambda}{8} = 8

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$1$

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(D) Given the mean of the data $7, 8, 9, 7, 8, 7, \lambda, 8$ is $8$.Mean $= \frac{7+8+9+7+8+7+\lambda+8}{8} = 8$$\Rightarrow \frac{54+\lambda}{8} = 8$$\Rightarrow 54+\lambda = 64$$\Rightarrow \lambda = 10$Now,the data set is $7, 8, 9, 7, 8, 7, 10, 8$.Variance $(\sigma^2) = \frac{1}{n} \sum (x_i - \bar{x})^2$Variance $= \frac{(7-8)^2 + (8-8)^2 + (9-8)^2 + (7-8)^2 + (8-8)^2 + (7-8)^2 + (10-8)^2 + (8-8)^2}{8}$Variance $= \frac{(-1)^2 + 0^2 + 1^2 + (-1)^2 + 0^2 + (-1)^2 + 2^2 + 0^2}{8}$Variance $= \frac{1 + 0 + 1 + 1 + 0 + 1 + 4 + 0}{8} = \frac{8}{8} = 1$.

Marks	$10-20$	$20-30$	$30-40$	$40-50$	$50-60$	$60-70$	$70-80$
Group $A$	$9$	$17$	$32$	$33$	$40$	$10$	$9$
Group $B$	$10$	$20$	$30$	$25$	$43$	$15$	$7$

If the mean of the data $7, 8, 9, 7, 8, 7, \lambda, 8$ is $8$,then the variance of the data is:

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