Question

A test consists of 910 true or false questions. If the student guesses on each question, what is the standard deviation of the number of correct answers?

Answer 1

15.083

Explanation:

For binomial random variable, standard deviation is given by :

`\sigma = \sqrt{ np(1-p) }`
`= \sqrt{910*(0.5)(1-0.5)} \\ = \sqrt{227.5} \approx 15.083103 \approx 15.083`