Question

In a given course a student receives preliminary examination grades of 81, 85, and 95. The final examination is weighed for one-third and the average of the preliminary grades is weighed as 2/3 of the final grade. What should the final examination grade be for a semester average of 90?

99
96
93
88
87

Answer 1

B. 96

Explanation:

Let x represent score of final third exam.

We have been given that in a given course a student receives preliminary examination grades of 81, 85, and 95.

Let us find average of preliminary scores.

`(81+85+95)/(3)=(261)/(3)=87`

We have been given that the final examination is weighed for one-third and the average of the preliminary grades is weighed as 2/3 of the final grade. This means that final grade is equally weighed into 3 parts. The two parts are 87 each and third part is x.

Using our given information, we can set an equation as:

`(87+87+x)/(3)=90`

`(174+x)/(3)=90`

`(174+x)/(3)*3=90*3`

`174+x=270`

`174-174+x=270-174`

`x=96`

Therefore, the final examination grade should be 96 for a semester average of 90.