Question

On a multiple choice test with 16 questions, each question has four possible answers, one of which is correct. For students who guess at all answers, find the standard deviation for the random variable X, the number of correct answers.

Answer 1

I'm taking a stab in the dark here...

The variance of a binomial distribution (which I'm pretty sure this is) can be found from V[x]=np(1-p). so V[x]=16(.25)(1-.25)=3. The Standard deviation is the square root of the variance. so about 1.7

This could very easily be wrong, been awhile since I've done this sort of problem