Final answer:
The subject of this question is Mathematics. The question involves finding the mean commute time for a given set of data. To find the mean travel time, you would calculate the sum of all the commute times and divide it by the total number of people.
Step-by-step explanation:
The subject of this question is Mathematics. The question involves finding the mean commute time for a given set of data. To find the mean travel time, you would calculate the sum of all the commute times and divide it by the total number of people. In this case, you would add up the commute times for each group (A, B, C, and D) and divide by 4 to find the mean travel time for each group.