In: Statistics and Probability
A sample of college students was asked how much they spent monthly on coffee. Approximate the standard deviation for the cost. Monthly coffee cost ($) Number of students 
10.00-19.99 6
20.00-29.99 20 
30.00-39.99 . 23 
40.00-49.99 18 
50.00-59.99 . 6
The sample standard deviation for the cost is  (Round to the nearest cent as needed.)