In a class in which the final course grade depends entirely on the average of four equally weighted 100-point tests, Paul has scored 75, 80, and 91 on the first three. What range of scores on the fourth test will give Paul a C for the semester (an average between 70 and 79, inclusive)? Assume that all test scores have a non-negative value.

Scores between 34 and 70 on the fourth test will give Paul a C for the semester.

Step-by-step explanation:

The average is given by the sum of all scores divided by the number of scores.

In this question:

Sum of all scores: 75 + 80 + 91 + x = 246 + x

Number of tests : 4

Grade of 70:

Grade of 79:

Scores between 34 and 70 on the fourth test will give Paul a C for the semester.

step-by-step explanation:

in the absence of parentheses, i will have to make some assumptions:   i interpret your (3x+5/y^6)(4y^3/5)​ to mean:

3x + 5     4y^(3/5)       (3x + 5)(4)

* =

    y^6             1               y^(6-3/5)

if this is not what you expected, repost your question using parentheses to indicate whether you meant

4y^3

    or   4y^(3/5)

    5