Question

Stu Dent received scores of 85, 78, and 81 on his first 3 exams in Algebra 1. What is the lowest score does Stu has to get on his 4th exam, so his test average would be at least an 84?

Answer 1

92

Explanation:

Given

Scores: 85, 78, 81

Required

Determine the least score in 4th subject is average must be at least 84

To solve this, we'll make use of Mean formula.

Mean = Sum of observations/Number of observations

We have that; Average = 84

Number of subjects = 4

Let the 4th subject be represented by F;

So, the sum of the four Subjects is:

Sum = 85 + 78 + 81 + F

Sum = 244 + F

Substitute these values in the above formula.

84 = ¼(244 + F)

Multiply both sides by 4

4 * 84 = 4 * ¼(244 + F)

336 = 244 + F

Subtract 244 from both sides

336 - 244 = 244 - 244 + F

92 = F

F = 92

To have an average of at least 84, Su's score must be atleast 92