Question

if the average of 3 numbers is 17 and that of the first two are 16,the third number is :

Answer 1

Let the third number be x.
Now average  = $\frac{x + 16 + 16}{3}$
⇒17 = $\frac{x + 32}{3}$
⇒17 × 3  =  x + 32
⇒ 51 = x + 32
⇒ x = 51 -32 = 19
⇒x = 19
 ∴ The third number is 19