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?
94 + 67 + 83 + 93 = 337
337/4 = 84
Where am I going wrong?
337 is her total score, and 84.25 is her current average up to the fourth test.
If she ended up with a grade of 90, that means her total score (for all five tests) is 5*90=450.
So what did she score in the final test?
113
113, did she get some bonus points or what?
In order to find out what Sarah got on the 5th and final test, we need to consider the total average of all 5 tests. Let's revise the calculation:
First, add up the scores of the 4 tests Sarah has grades for: 94 + 67 + 83 + 93 = 337.
Now, to find the average score of the 4 tests, we divide the total sum by the number of tests taken: 337 / 4 = 84.25.
Keep in mind that the average of the 4 known tests is 84.25, not exactly 84.
The problem states that Sarah ended up with a grade of 90 for the entire course.
Therefore, let's solve for Sarah's score on the 5th test.
To get the sum of all 5 tests, we multiply the average score (84.25) by the total number of tests, which is 5: 84.25 * 5 = 421.25.
Now, let's subtract the sum of the 4 known tests (337) from the sum of all 5 tests (421.25) to find out Sarah's score on the 5th test: 421.25 - 337 = 84.25.
So, Sarah got a score of 84.25 on the 5th and final test.