1. The problem statement, all variables and given/known data A die is biased such that the probability of getting a six is 1/4. The die is rolled 2000 times. Let X be the number of sixes obtained. Find, a) the mean of X b) the standard deviation of X, leaving your answer as a surd. 2. Relevant equations 3. The attempt at a solution a) The mean of X is simple, given P(6)=1/4, and the dice is rolled 2000 times, the mean of X is 2000(1/4)=500 b) This is where I don't know what to do. Any guidance?