Question

The average of 5 numbers is 18. When a sixth number is added,the average is 17. Calculate the value of the sixth number.

Answer 1

Step-by-step explanation:

let the sum of $5$ numbers be $x$.

therefore,

$\frac{x}{5} = 18$

=> $x = 90$

let the sixth number be $y$.

therefore,

$\frac{x + y}{2} = 17$

=> $\frac{90 + y}{6} = 17$

=> $90 + y = 102$

=> $y = 102-90 =12$

thus, sixth number is $12$.

Answer 2

answer:

12

explanation:

Let first five no. are a, b, c, d, e

average of 5 no. = ( a+b+c+d+e ) / 5 = 18

then, a+b+c+d+e = 18 * 5 = 90

, and let 6th no. be f

average of 6 no. = ( a+b+c+d+e+f) / 6 = 17

then, a+b+c+d+e+f = 17 * 6

a+b+c+d+e+f = 102

From above put value of a+b+c+d+e

90 + f = 102

f = 102 - 90

f = 12