Answer:
answer should be 52.4 mins
Explanation:
find the midpoint for each time:
1. 15mins = 7students
2. 45mins = 27 students
3. 75mins = 12 students
4. 100 = 4students
Then, do the normal mean calculation by adding up all the values and dividing it by 50.
7*15 + 27*45 + 12*75 + 100*4 = 2620
2620/50 = 52.4mins