You have a 5
-
question multiple
-
choice test. Each question has four choices. You don’t
know any of the answers. What is the experimental probability that you will guess exactly
three out of five questions correctly?

Question

You have a 5
-
question multiple
-
choice test. Each question has four choices. You don’t 
know any of the answers. What is the experimental probability that you will guess exactly 
three out of five questions correctly?

alexandervonhumboldt2 · Answer

first we need to find how many choices there are in 5 questions. It will be 5*4=20. So there are 20 choises in all questions. Now we have to guess 3 choices correctly out of 20:
so  it will  be 3/20 i think

alexandervonhumboldt2 · Answer

@zepdrix  i'm not sure i did this correctly

anonymous · Answer

That's how I did it, but I was unsure

alexandervonhumboldt2 · Answer

ok

zepdrix · Answer

I've never been very good at these probability questions >.< Grrr

I'm thinking it's more along these lines:
The odds of getting a single question correct is 1/4.
So the odds of getting three questions right is (1/4)(1/4)(1/4).

zepdrix · Answer

Blah, I dunno :)