Statistics
posted by chalulu .
A test consists of 90 mulitiple choice questions, each with five possible answers, only one of which is correct. Find the mean and the standard deviation of the number of correct answers.

mean = np = 90 * 1/5 = ?
(Note: convert any fractions to decimals.)
standard deviation = √npq = √(90 * 1/5 * 4/5) = ?
(Note: q = 1  p)
I'll let you take it from here.