The average of your first 6 tests is 82. If your test average after your seventh test is an 80.5, what did you score on the seventh test?

Question 2 options:

So average is of the first 6 tests is 82 well that means

(test1 + test2 + test3 + test4 + test5+test6) / 6 = 82

so now let do some cross multiplliying

test1 + test2 + test3 + test 4 + test5 + test6 = 82*6

test1 + test2 + test3 + test 4 + test5 + test6 = 492

now lets see if we can find that 7th test score

(test1 + test2 + test3 + test4 + test5 + test6 + test7) / 7 = 80.5

So look we found test1 + test2 + test3 + test4 + test5 + test6 to be 492 so lets substitute.

(492 + test7) / 7 = 80.5

test7 = (80.5*7) - 492 = 71.5