If the student guesses what is the probability that he will

If the student guesses, what is the probability that he will get exactly 10 questions right?

Solution

Binomial Distribution

PMF of B.D is = f ( k ) = ( n k ) p^k * ( 1- p) ^ n-k
Where     
k = number of successes in trials        
n = is the number of independent trials        
p = probability of success on each trial

P( X = 10 ) = ( 12 10 ) * ( 0.5^10) * ( 1 - 0.5 )^2
= 0.0161