Final answer:
The mean number of lemons is 13. To find the mean number of lemons, add up the numbers and divide by the total count.
Step-by-step explanation:
The mean, or average, of a set of numbers can be found by summing all the numbers and then dividing the sum by the total number of values. In this case, we have the following numbers of lemons: Winter 3, Spring 15, Summer 21, and Fall 13. To find the mean, we add up these numbers: 3 + 15 + 21 + 13 = 52. There are a total of 4 seasons, so we divide 52 by 4 to find the mean: 52/4 = 13. Therefore, the mean number of lemons is 13.