A random sample of 60 students in the business statistics course answered a survey on the average number of hours they spent on statistics each week. Unfortunately, the original data was lost and all that remains is the frequency table below. From these data, calculate the estimated sample standard Class 1 2 3 4 5 deviation. Hrs 0-3 4-7 8-11 12-15 16-19 18 16 14 10 2 60 Mid t 1.5 5.5 9.5 13.5 17.5 27 88 133 135 35 418