Question: The table relates the response to a fund-raising appeal by a college to its alumni to the number of years since graduation.
An alumnus is selected at random. Adjoin the row and column totals to the table and use the expanded table to find the probability of each of the following events.
a. The alumnus responded.
b. The alumnus did not respond.
c. The alumnus graduated at least 21 years ago.
d. The alumnus graduated at least 21 years ago and responded.