Question

Roger gets quiz grades of 90, 68, and 80. He gets a 71 on his final exam. Find the weighted mean if the quizzes each count for 10% and the final exam counts for 70% of the final grade. What is his letter grade?

Answer 1

To calculate the weighted mean, you have to multiply each score by the corresponding percentage (expressed as a decimal value) and then add the results.

For the final grade, you know that the grade in each quiz counts for 10% of the final grade. So you have to multiply the score of each quiz by 0.10.

The final exam counts for 70% of the final grade, which means that you have to multiply the grade by 0.7.

`\begin{gathered} \bar{X}=0.1\cdot90+0.1\cdot68+0.1\cdot80+0.7\cdot71 \\ \bar{X}=9+6.8+8+49.7 \\ \bar{X}=73.8 \end{gathered}`

The weighted mean is equal to 73.8.

The letter grade corresponds to C.