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This question isn't in a book, but I want to know the answer for myself.

Q. If I take an MCQ test with 40 questions, each question has 4 possible answers with only one being correct, what is the probability of getting 40/40 in the test by guessing?

I've tried solving this by doing (1/4)^40, but then I thought of doing 1/(160C40) and I got different answers. Why is that so and which is the correct way.

Q. If I am sure of 30 questions and unsure about 10 (have to guess them), what is the probability of getting above 30 in the test.(I don't lose marks for wrong answers)

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# Homework Help: Probability of MCQ

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