Shirts sold

In analyzing the sales of the last 200 dress shirts sold at a large men’s wear retail outlet, the manager created the following frequency table.
Shirt Size Frequency
Small 15
Medium 70
Large 85
Extra Large 30
Figure 1. Frequency table.
When the next customer walks in to buy a dress shirt, find the probability that:
a. The customer will buy a large dress shirt.
b. The customer will not buy a small dress shirt.
c. What type (concept) of probability are you using in determining your answer to part a above? Briefly explain.