Colin predicted whether he got answers right or wrong in his 50 question exam. He identified the 12 questions he thought he got wrong.

It turns out that Colin got 5 questions right that he thought he got wrong.

Colin also got a total score of 42 out of 50 in the test.

What is the percentage accuracy he had with predicting his scores?

Step-by-step explanation:

so, he predicted he had 12 questions wrong.

that would have been a score of 38.

but he got 42.

that is a difference of 42-38 = 4.

now, accuracy could have different meanings like actual score vs. predicted score, or which questions were right or wrong (for real or predicted), or only looking at the questions that were right (real vs. predicted), ...

I assume it is the first one.

so,

100% = 38 (prediction)

1% = 100%/100 = 38/100 = 0.38

how many % are these 4 questions that his prediction was off from reality ?

4 / 0.38 = 10.52631579...

so, his prediction was off by about 10.53%

b. 153 students do not participate in sports and seventy-five 12th graders were surveyed