The frequency distribution shows the waiting times (in minutes) for 50 patients at a walk-in medical facility. Construct a histogram, frequency polygon, and ogive for the data. Is the distribution skewed? How many patients waited longer than 30 minutes?

Class limits                     Frequency
11–15...............................................7
16–20...............................................9
21–25.............................................15
26–30...............................................9
31–35...............................................5
36–40...............................................3
41–45...............................................2
...............................................Total 50