probability: If several students took a true/false quiz,....

hello I would like somehelp on the following question.

If several students took a quiz that has 45 question and it was true/flase test, and all answers are guesses. how would I find the mean, variance , and standard deviation for the number of correct answer for each inidivdual student.

I just don't know what formula to use and how i would com up with the numbers to plug in with this limited amount fo information. Please help

For a binominal random variable with probability of success, p, and N number of trials, the mean is Np and the variance is Np(1-p),

Here N=45 & p=0.5.

thank you so much that makes sense. I was thinking like that but I only got to the mean. Thanks a million