The manager of a supermarket records the waiting times of 100 customers. He wishes to calculate an estimate for the mean waiting time.
He draws this table.
Waiting Time
Number of
Midpoint (x)
fx
(minutes)
customers (0)
0 -
0.5
5
2.5
1 -
1.5
28
2 -
2.5
32
3-
3.5
26
4-5
4.5
9
100
did the table need help working out the estimate for the mean