Jim has grades of 84, 65, and 76 on three math tests. What grade must he obtain on the next test to have an average of exactly 80 for the four tests?
Well first you add up the currently known grades: 84, 65, and 76. (known grades)
Next multiply 80 by 4 to get the total amount for his test scores. (wanted average)
Finally subtract the total for his known grades from his wanted average.
4 * 80 = 320
84 + 65 + 76 = 225
320 - 225 = 95
To find out what grade Jim must obtain on the next test to have an average of exactly 80 for the four tests, we need to calculate the total score he needs to achieve.
First, let's find the total score Jim already has.
Jim's grades on the first three math tests are 84, 65, and 76.
Total score = 84 + 65 + 76 = 225
Now, let's calculate the score Jim needs on the next test to have an average of 80.
Average score of all four tests = 80
Total score of all four tests = Average score x Number of tests
Total score of all four tests = 80 x 4 = 320
To find the score Jim must obtain on the next test:
Score needed on the next test = Total score of all four tests - Total score Jim already has
Score needed on the next test = 320 - 225 = 95
Jim must obtain a grade of 95 on the next test to have an average of exactly 80 for the four tests.