Considering the given table, we have that:
a) The modal class is 24-26.
b) The estimate of the mean is of 23 years.
The modal class of a frequency table is the class that has the most observations. In this problem, the class is of 24-26, as it has 8 observations, being the largest number.
The expected value of a discrete distribution is given by the sum of each outcome multiplied by it's respective probability.
From the frequency table, consisting of 20 observations, a discrete distribution can be built, considering the half-way point of each interval. Then:
Then the estimate of the mean is:
E(X) = 0.15 x 19 + 0.1 x 21 + 0.35 x 23 + 0.4 x 25 = 23 years.
More can be learned about the mean of a discrete distribution at https://brainly.com/question/24628525
#SPJ1