Question

Kara has five exam scores of 75, 83, 84, 84, and 74 in her biology class. What score does she need on the final exam to have a meangrade of 70 round your answer to two decimal places, if necessary. (All exams have a maximum of 100 points.

Answer 1

Let marks acquired in 6th test equal to x. Since the mean is the sum of observations divided by the total number of observations, we have

`\text{ mean=}(75+83+84+84+74+x)/(6)`

which gives

`mean=(400+x)/(6)`

By substituting the given mean value , we get

`70=(400+x)/(6)`

Then, by multiplying both sides by 6, we have

`420=400+x`

then, x is given by

`\begin{gathered} x=420-400 \\ x=20 \end{gathered}`

Then, Kara will have to score 20 marks in the final test to get the desired mean value.