Answer:
The mean of the data set is 56.42.
The mean signify that the average age of college professors is about 56 years.
Explanation:
The given stem-and-leaf plot represents the ages of college professors.
From the given stem-and-leaf plot we get the data set
30,32, 41, 44, 44, 45, 53, 55, 58, 59, 62, 62, 62, 65, 66, 68, 75, 75, 76
The formula for mean is

where, x are observations and n is sample size.
Using the formula, the mean of the given data set is



The mean of the data set is 56.42.
The mean signify that the average age of college professors is about 56 years.