Question

the average of three number is 25. two of the number are 18 and 40. what is the third number

Answer 1

Given data:

The given average of three numbers is x=25.

The first number is a=18.

The second number is b=40.

The expression for the avearge of three numbers is,

$\frac{a+b+c}{3}=x$

Substitute the given values in the above expression.

$\begin{gathered} \frac{18+40+c}{3}=25 \\ 58+c=75 \\ c=17 \end{gathered}$

Thus, the third number is 17.