Consider the experiment of tossing a fair coin three times and observing the number of heads that result (X = number of heads).What is the standard deviation for this distribution?
A)1.5
B)1.22
C)0.75
D)0.87

Question

Quizplus · Accepted Answer

The distribution of the number of heads in three tosses of a fair coin is a binomial distribution with parameters n=3 and p=0.5. The formula for the standard deviation of a binomial distribution is:

SD = sqrt(np(1-p))

Plugging in n=3 and p=0.5, we get:

SD = sqrt(3*0.5*(1-0.5)) = 0.866

So the standard deviation is 0.87, which is closest to choice D.

Consider the Experiment of Tossing a Fair Coin Three Times