Question

Jenny has five exam scores of 81, 89, 92, 85, and 66 in her biology class What score does she need on the final exam to have a mean grade of 80? Round your answer to two decimal places, if necessary (All exams have a maximum of 100 points.) Keypad

Answer 1

Let:

x6 = Final score

The mean is given by:

`\begin{gathered} \mu=(x1+x2+x3+x4+x5+x6)/(6) \\ where\colon \\ \mu=80 \\ x1=81 \\ x2=89 \\ x3=92 \\ x4=85 \\ x5=66 \end{gathered}`

Solve for x6:

`\begin{gathered} 80=(81+89+92+85+66+x6)/(6) \\ 80\cdot6=413+x6 \\ 480-413=x6 \\ x6=67 \end{gathered}`

She needs a 67 on the final exam