Question

According to a 2016 survey, 6 percent of workers arrive to work between 6:45 A.M. and 7:00 A.M. Suppose 300 workers will be selected at random from all workers in 2016. Let the random variable W represent the number of workers in the sample who arrive to work between 6:45 A.M. and 7:00 A.M. Assuming the arrival times of workers are independent, which of the following is closest to the standard deviation of W?

A. 0.24
B. 4.11
C. 4.24
D. 16.79
E. 16.92

Answer 1

Answer: B. 4.11

Explanation:

Using Binomial distribution ( as the arrival times of workers are independent).

Formula for standard deviation:
`\sqrt{{p(1-p)}{n}}`, where p= population proportion, n= sample size.

As per given ,

p= 0.06, n=300

Required standard deviation=
`√(0.06\left(1-0.06\right)300)`

`=√((0.06)(0.94)(300))\\\\=√(16.92)\approx4.11`

Hence, the correct option is B.