Question

$p,q,r,s,t$ are five numbers such that the average of $p,q$ and $r$ is $5$ and that of $s$ and $t$ is $10$. What is the average of all the five numbers ?

• A. $7.75$
• B. $7.5$
• C. $7$
• D. $5$

Answer 1

The correct option is C $7$

Average of terms $=\frac{\text{sum of terms}}{\text{number of terms}}$

$\Rightarrow \frac{p+q+r}{3}=5\Rightarrow p+q+r=15$

and

$\frac{s+t}{2}=10\Rightarrow s+t=20$

So, $average=\frac{p+q+r+s+t}{5}$

$=\frac{15+20}{5}=7$