You can put this solution on YOUR website!
You calculated the mean number of deaths correctly.
Regarding the standard deviation, notice that the number of deaths follows a binomial distribution, with parameters n = 100 (the total number of patients) and p = 0.7 (the probability of a "success", in this case, that the patient dies, which is 70%). The variance of variable that follows a binomial distribution is given by:
Pluging the appropiate parameters,
Finally, since the standard deviation is the square root of the variance, the we get that the std dev of the number of deaths is:
I hope this helps!
Get more answers at Online Math Answers.com