Sarah was trying to figure out her grades for her math course. she only knew the grade of 4 of the tests she had taken, However the class had taken 5 tests total. She scored a 94, 67, 83, and 93. If Sarah ended up with a grade of 90, what did she get on the 5th and final test?

How do I solve this problem?

94+67+83+93 = 337

5*90 = 450

Looks like she needed a 113 on the final test. I suspect a typo. Fix it and redo the math.

To solve this problem, you need to find the score Sarah obtained on the 5th and final test. Since Sarah had only known the grades of 4 tests, you can use the average of these four test scores to determine her current average. Then, you can use the formula to find the score she needs on the 5th test in order to achieve the desired average of 90.

Let's break down the steps:

Step 1: Find the average of Sarah's known scores by adding them together and dividing the sum by the number of tests (4 in this case).
(94 + 67 + 83 + 93) / 4 = 337 / 4 = 84.25

Step 2: Determine the total points Sarah needs to get on all five tests in order to achieve an average of 90. Multiply the desired average by the total number of tests.
90 x 5 = 450

Step 3: Calculate the score Sarah needs to get on the 5th test by subtracting the sum of her known test scores from the total points needed.
450 - 337 = 113

Therefore, Sarah needs to get a score of 113 on the 5th and final test to achieve an average grade of 90 in her math course.