Question

If mean (x) pom 15, Efx = 342 + a and N = 20 + a, find the value of a.​

Answer 1

a = 3

Explanation:

mean is calculated as

mean =
`(sum)/(count)`

Here mean = 15, sum = 342 + a and count = 20 + a , then

`(342+a)/(20+a)` = 15 ( multiply both sides by 20 + a )

342 + a = 15(20 + a) ← distribute

342 + a = 300 + 15a ( subtract a from both sides )

342 = 300 + 14a ( subtract 300 from both sides )

42 = 14a ( divide both sides by 14 )

3 = a