# The average of the first 7 numbers was 21. The average of the next 3 numbers was only 11. What was the overall average of the numbers?

Dec 12, 2016

The overall average is $18$.

#### Explanation:

If the average of $7$ numbers is $21$, it means the total of the $7$ numbers is $\left(21 \times 7\right)$, which is $147$.

If the average of $3$ numbers is $11$, it means the total of the $3$ numbers is $\left(11 \times 3\right)$, which is $33$.

The average of the $10$ numbers $\left(7 + 3\right)$ will therefore beL

$\frac{147 + 33}{10}$

$\frac{180}{10}$

$18$