CAT 2018 Slot 1 QA Question 34: A CAT aspirant appears for a certain number of tests. His average score increases by 1 if the first 10 tests are not considered, and decreases by 1 if the last 10 tests are not considered. If his aver

Question

A CAT aspirant appears for a certain number of tests. His average score increases by 1 if the first 10 tests are not considered, and decreases by 1 if the last 10 tests are not considered. If his aver

Accepted Answer

Let the total number of tests be n and the overall average score be A.
Total score $=nA$
Average of the first 10 tests is 20, so their total score is 200.
Excluding the first 10 tests, the average increases by 1.
$nA - 200 = (n - 10)(A + 1)$
$n = 10A - 190$
Average of the last 10 tests is 30, so the