Total questions, T = 50.
Colin thought 8 questions were right.
Colin got 5 questions right that he thought he got wrong.
Total score, s = 45.
So, actual number of questions which are wrong are 5.
Score according to him = 50 - 8 = 42.
Now, we know percentage accuracy is given by :
[tex]\% =100- \dfrac{|Actual\ value-Theoretical\ value|}{Actual\ Vlaue}\times 100\\\\\%=100-\dfrac{|45-42|}{42}\times 100\\\\\%=100-7.14 \%\\\\\%=92.86\%[/tex]
Therefore, percentage accuracy he had with predicting his scores is 92.86%.
Hence, this is the required solution.