The most popular names for babies born in the United Kingdom in 2012 were Harry and Amelia.Of the roughly 400,000 baby boys born in the UK in 2012, two percent were named Harry, while two percent of the girls born that year were named Amelia (Source: UK Office for National Statistics, Baby Names, England and Wales, 2012).Suppose that 20 baby boys are chosen at random.Let X represent the number of boys named Harry.What is the standard deviation of X?
A)4.472
B)0.179
C)0.040
D)0.032
E)1.360

Question

Quizplus · Accepted Answer

The standard deviation of a binomial distribution is the square root of np(1-p), where n is the number of trials and p is the probability of success. In this case, n = 20 and p = 0.02, so the standard deviation is sqrt(20 * 0.02 * 0.98) = 0.179.

The Most Popular Names for Babies Born in the United