Question

If mean of $x_1,x_2,x_3,......x_{20}$ is $25$, then $\sum _{i=1}^{20}(x_i-25)$=?

• A. $20$
• B. $0$
• C. $25$
• D. $Noneofthese$

Answer 1

Answer: (B)

$0$

Mean of $x_1{x}_2,x_3....x_{20}$ is $25$

$\therefore \frac{x_1+x_2+x_3+x_4......+x_{20}}{20}=25$

$\therefore x_1+x_2+x_3+x_4+x_5+.....x_{20}=25\times 20$

$\therefore x_1+x_2+x_3+x_4+.....x_{20}=500$

$\therefore \sum _{l=1}^{20}(x_i-25)=(x_1+x_2+x_3+....x_{20})-(25\times 20)$

$500-500$

$=0$