An exam has ten true-false questions. A student who has
not studied answers all ten questions by just guessing. Find
the probability that the student correctly answers the given
number of questions.
(a) All ten questions
(b) Exactly seven questions

Question

An exam has ten true-false questions. A student who has
not studied answers all ten questions by just guessing. Find
the probability that the student correctly answers the given
number of questions.
(a) All ten questions
(b) Exactly seven questions

anonymous · Answer

A 50% 
B IDK

anonymous · Answer

How did you get the answer? Can you show the method?

anonymous · Answer

a) P ( x = 10 ) = .5^ 10
b) P ( x = 7) =  10 C 7 * ( .5)^10

anonymous · Answer

Still not clear to me. :(

experimentx · Answer

http://en.wikipedia.org/wiki/Binomial_distribution

experimentx · Answer

a case of binomial probability

anonymous · Answer

Chlorophyll gave you the equation all he/she did was solve

anonymous · Answer

I don tnow how to explain it better! Sorry!

anonymous · Answer

Since all questions have equal % of true or false 50% = .5
There are total 10 
Thus P( X ) = .5 ^10 = .098% 
By guessing, your chance of answering all ten right is very thin, not even 1%