Question

David has earned the following test

grades: 89, 96, 99, 85. What is the
grade David has to earn on his 5th test to maintain a test
average of 90?

Answer 1

81

Explanation:

Required average= 90

let the required grade be x

Average= Sum of n numbers

90= 89+96+99+85+x divide by 5

450= 369+x

x = 450-369

x=81