Question

The average of 3, 15, and my number is 40. What is my number?

Answer 1

$\textbf{Concept used:}$

$\text{Average of the given n numbers x_1,x_2,.......x_n is}$

$\overline{x}=\frac{\Sigma{x_i}}{n}$

$\text{Let the my number be x}$

$\text{Given: Average of 3, 15 and x is 40 }$

$\implies\displaystyle\frac{\Sigma{x_i}}{n}=40$

$\implies\displaystyle\frac{3+15+x}{3}=40$

$\implies\displaystyle\,18+x=120$

$\implies\displaystyle\,x=120-18$

$\implies\bf\,x=102$

$\therefore\textbf{My number is 102}$

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The avarage of four consecutive even numbers p,q,r and s respectively in 51.what is product of p and r.

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