Question

Michael's average score I four test is 65. if he wants to raise his overall average by 5 Points what score must he get in his fifth test?

Answer 1

Given
(a+b+c+d)/4 = 65
a+b+c+d = 65 × 4 = 260

ATQ
(a+b+c+d+e)/5 = 65 + 5
a+b+c+d+e = 70 × 5
260 + e = 350
e = 90
Therefore, he should score 90 points in the fifth test to raise his overall average by 5 points

Answer 2

(x1+x2+x3+x4 )÷ 4 =65 ................................(1)
so
x1+x2+x3+x4=260 ...............................................(2)

(x1+x2+x3+x4+x5) ÷ 5 = 70 .............................(3)
so

x1+x2+x3+x4+x5=350
from eq 2 & 3

260+x5=350
x=350-260
x=90