# I need help with a statistics problem

**Question description**

An instructor has found that grades on the final exam for a course are normally distributed with a mean of 63 (out of 100) and a standard deviation of 11.5. The pass mark for the exam is 50.

The exam consists of 24 multiple-choice questions, each with 3 possible answers of which only 1 is correct.

Part 1 - How many students in a typical class of 30 would you expect to fail?

Part 2 - A student knows the answer to 12 of the questions, but has to guess at the other 12. What’s the probability that this student ends up in the top 10% of the class?

## Tutor Answer

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