Answer:
He needs to score 100 in his next test.
Step-by-step explanation:
The average of the exams is given by the sum of each exam score divided by the number of exams he took, therefore his prior average is:
[tex]\text{prior average} = \frac{\text{prior sum of grades}}{\text{prior number of tests}}[/tex]
Since he took five exams and had an average of 88, then his prior sum of grades is:
[tex]\text{prior sum of grades} = 88*5 = 440[/tex]
He needs to score "x" in his next test in order to have an 90 average, therefore if we add "x" to the sum of his grades and add 1 to the prior number of tests then equal that to 90, we can solve for "x". We have:
[tex]\text{desired average} = \frac{\text{prior sum of grades} + x}{\text{prior number of texts}+1}\\90 = \frac{440 +x}{6}\\440 + x = 90*6\\x = 540 - 440\\x = 100\\[/tex]
He needs to score 100 in his next test.
