Blair’s average (arithmetic mean) on two physics tests is 7. What should Blair’s score be on the next test to have an overall average of 8 for all the tests?

Blair’s average (arithmetic mean) on two physics tests is 7. What should Blair’s score be on the next test to have an overall average of 8 for all the tests?

Detailed Explanation

The arithmetic mean is defined as the sum of the terms divided by the number of terms. To have an overall average of 8, \([ \frac{\mathrm{7 \times 2+x} }{\mathrm{3} } = 8 ] \) then x=10.