If you earn the grades of 81, 84, 78, 80 in four tests what should your final test’s score be in order to have an average of 81%?

.81x400=324
Need a total of 324 pts
Test grades so far 81,84,78,80 = 323
324-323=1
You need at least one more point to get an 81

Can someone please check my problem to see if it is correct if not please guide me thank you

Isn't your final grade figured on five tests?

0.81 * 500 = 405

405 - 323 = 82

ok so instead of .81 x 400 it's 500? because it is 5 tests?

Right.

ok thank you

You're welcome.

Your approach is correct! To calculate the required score on the final test, you first need to find the total number of points required to achieve an average of 81%. Since the total number of tests is 5 (including the final test), the total number of points required would be 81% of 500 (5 tests x 100 points each).

81% of 500 is (81/100) x 500 = 405.

Next, you sum up the scores of the previous four tests, which is 81 + 84 + 78 + 80 = 323.

To find the score you need on the final test, you subtract the total score obtained from the desired total score:

405 - 323 = 82.

Therefore, you would need to score at least 82 on the final test in order to have an average of 81%.