Question

A student has a 90, 84, and an 86 on their first 3 tests. What possible scores would the student need

to make on the 4th test to bring his test average up to a 90? Choose all answers that apply.
a. 90
b. 94
c. 100
d. 98

Answer 1

To bring the test average up to 90, the student would need to score 100 on the fourth test.

Step-by-step explanation:

In order to bring the test average up to 90, we need to find the score the student would need to achieve on the fourth test. Let's calculate:

1. Sum up the scores from the three tests: 90 + 84 + 86 = 260.
2. Divide the sum by the number of tests: 260 / 3 = 86.66 (rounded to two decimal places).
3. The student's current average is 86.66.
4. To bring the average up to 90, the total sum of all four tests needs to be 90 multiplied by 4 = 360.
5. Subtract the sum of the three previous tests from the required total sum: 360 - 260 = 100.

Therefore, the student would need to score 100 on the fourth test to bring their test average up to 90.

Answer 2

The student would need to score a 100 on the 4th test to bring the test average up to 90. Option C is answer.

Step-by-step explanation:

Let x be the score needed on the 4th test to achieve an average of 90.

The average is calculated as the sum of all test scores divided by the number of tests. For this scenario:

(90 + 84 + 86 + x) / 4 = 90

Simplify the equation:

90 + 84 + 86 + x = 360

260 + x = 360

Solve for x:

x = 100

Therefore, the student would need to score a 100 on the 4th test to attain an average of 90. Option c (100) is the correct answer.