The probability of rolling a 2 is 1/6. If X is a random variable representing the number of 2s that are obtained after rolling a die 23 times, then X follows a binomial distribution with success probability p = 1/6 across n = 23 trials.
The variance of a binomial distribution with parameters p and n is n p (1 - p), so the standard deviation in this case would be
√(23 • 1/6 • 5/6) ≈ 1.8
