Question

If the mean of a set of observations $x_1,x_2,x_3,...,x_{10}$ is $20$, then the mean of $x_1+4,x_2+8,x_3+12,...,x_{10}+40$ is

• A. $34$
• B. $42$
• C. $38$
• D. $40$

Answer 1

Answer: (B)

$42$

Mean, $\overline{x}=\frac{1}{10}\left[\right(x_1+x_2+x_3+....+x_{10})+(4+8+.....+40)]$
$=20+\frac{1}{10}\times \frac{4\times 10\times 11}{2}=42$