Posted by **Jamal** on Tuesday, April 22, 2008 at 4:51pm.

What is the probability of guessing 70 out of 100 multiple choice questions correct when there are 4 choices per question?

- math -
**Reiny**, Tuesday, April 22, 2008 at 6:05pm
prob of being right is 1/4

prob of guessing wrong is 3/4

so prob of guessing 70 out of 100 correct is

C(100,70)*(1/4)^70*(3/4)^30

= 3.763*10^-21

we are dealing with very large and very small numbers here, and I had to "trust" my calculator.

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