Question

Brett golfs for the forestville knights high school team. When he practices his putting, he can make a 10-foot putt 80% of the time. If Brett takes 200 putts for practice, what is the standard deviation of the number of putts he will make?

Answer 1

The formula to calculate standard deviation from probability is \sqrt(n*p*(1-p)). n is the sample size, and 200 in this case (number of putts for practice). p is 80% or 0.8, the probability that he can make it. So the standard deviation is \sqrt(200*0.8*(1-0.8)=\sqrt(200*0.8*0.2)=\sqrt(16)=4.