Question

Russells previous test scores are 70,74,87,85 what score does he need to get an average of 80

Answer 1

70+74+87+85 = 316
For the 5th test score, an 80 average needs 400 as the total score. So 400-316 = 84 on the next test.

Answer 2

84 is the score that you Russell needs on the next test to achieve an average of at least 80.

Explanation:

Russell's test scores are: 70,74,87 and 85

Average of the test scores = A = 80

Let thescore needed to achieve an average of 80 be x

Average =
`\frac{\text{Sum of terms}}{\text{Number of terms}}`

`A=(70+74+87+85+x)/(5)`

`80=(70+74+87+85+x)/(5)`

`70+74+87+85+x=400`

`x=400-(70+74+87+85)=84`

84 is the score that you Russell needs on the next test to achieve an average of at least 80.