You are asked to gather some data on wait times for a popular rollercoaster at the amusement park where you work. You can't track the waiting time of every rider, so you decide to sample 81 people at random each day. The mean of a distribution of sample mean wait times is 18 minutes and the standard deviation of the sampling distribution (sigma subscript x with bar on top end subscript) is 0.5 minutes. What is the standard deviation of the population (sigma)? 0.5 4.5 18 2