Question

If Joseph gets 71 on his next test his average will be 83 if he gets 99 his average will be 87.How many years has Joseph already taken?

Answer 1

83x-71=87x-99
x=7...........

Answer 2

Let the total number of tests taken be X

total marks obtained test be Y.

ATQ,

(Y+71)/X = 83

Y + 71 = 83N

Y = 83N - 71 ........(1)

And,

(Y+99)/X = 87

Y + 99 = 87N

Y = 87N - 99 .......(2)

Subtracting equation (1) from equation (2), we get

Y= 87X-99-(83N-77)

4X - 28 = 0

4X = 28

X = 28/4

X =7