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 ?