Answer: Mean = 52.8 mins
Step-by-step explanation:
We have lapses of 30 minutes, so we can write the average for each, this means that:
0 < t < 30 can be averaged to the middle of the range: 15 min.
Doing this, we have that:
7 students 15 min
27 students 45 min
12 students 75 min
4 students 105 min.
Now we can calculate the mean:
mean = (x1*n1 + x2*n2 + ...)/N
where x1 is the amount of time 1, and n1 is the number of students associated to that time and so on. N is the total number of students
Mean = (7*15min + 27*45min + 12*75min + 4*105min)/(7 + 27 + 12 + 4)
Mean = 52.8 mins
