If I score a 79% on a test, and retest only only the 21% with a score of 79%, what is my new overall score?

Question

I scored 79 perecent on a test.

 

The retest was only on the 21% that I answered incorrectly. My score for that test was 79%.

So, what is my new overall score for the entire test?

Answer 1

To make it easy, assume there were 100 questions in the original test, so 21 would be wrong.

When tested on the 21 incorrectly answered, 79% of 21=16.59 were answered correctly.

All together, 79+16.59=95.59 questions would be answered correctly, 95.59%.

Another way to solve: the total loss of marks is 21% of 21%=4.41% so that gives a score of 100-4.41=95.59%.