Suppose you are taking a true-false test with twelve questions. If you guess at the answers on this test, find the probability of getting exactly eight correct answers

Question

anonymous · Answer

1/2 chance of getting 100

anonymous · Answer

Exactly eight correct answers

anonymous · Answer

forgot to finish question-lol

anonymous · Answer

im not sure about it I think it would be 8/12 cuz you got 2 correct which is also 2/3

anonymous · Answer

cuz you got 8*

anonymous · Answer

how would I round that to three decimal points?

anonymous · Answer

0.08

raden · Answer

number events of (T T T T T T T T F F F F) = 12!/8!4! = ...
it is a start

anonymous · Answer

ty

anonymous · Answer

Direct application of binomial distribution with n=12, p=1/2. Plug in the numbers yourself!

raden · Answer

then we knowed that the probability if the correct answer also incorrect answer is 1/2 resfectively, and assumed this case is independet event.
so, the probability of P(8T's and 4F's) = (1/2)^12 * 12!/8!4! = ...

raden · Answer

@MistrisKat , did u get it what's the value of 12!/8!4! = ...

raden · Answer

do u know about factorial ?

anonymous · Answer

not really :(

anonymous · Answer

am I multiplying 12 x 8x4?

anonymous · Answer

not sure what the ! is doing in there, what it's function?

anonymous · Answer

factorials are like 8.7.6.5.4.3.2.1. right?

raden · Answer

yep, that's right
so, what's the value of
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anonymous · Answer

working on it just downloaded a fractional calculator..

anonymous · Answer

12=479001600

anonymous · Answer

not sure how to do bottom piece.  separately 8=40320 and 4 =24

raden · Answer

easier if u doing cancel out for the similar term :
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