A major ski resort in the eastern United States closes in late May. Closing day varies from year to year depending on when the weather becomes too warm for making and preserving snow. The day in May and the number of years in which closing occurred that day are reported in the table:
Day Number of Years
21 ...... 2
22 ...... 5
23 ...... 1
24 ...... 3
25 ...... 3
26 ...... 1
27 ...... 2
28 ...... 1
a. Based only on this information, estimate the probability that you could ski at this resort after May 25 next year.
b. What is the average closing day based on history?