Question

Question #6bcb7

Answer 1

81.25

Explanation:

This kind of problem makes you think you'll need to know how many students are in the class, but as it turns out, you don't need to know it.

Say `n` is the number of students in the class. If 75% of the `n` students had an average score of 82, then we can find the sum of the scores in that group by multiplying the average by the number of students in that group:

`S_1 = (.75n)(82) = 61.5n`

Next, the remaining portion of students (which would be 25% of the `n` students), had an average of 79, making their sum of scores:

`S_2 = (.25n)(79) = 19.75n`

To find the overall class average we add all the scores together and divide by the number of students:

`Avg. = (S_1 + S_2)/n = (61.5n+19.75n)/n = (81.25n)/n = 81.25`