The number of arrivals per minute at a bank located in the central business district of a large city was recorded over a period of 200 minutes, with the following results:
Arrivals Frequency
0 14
1 31
2 47
3 41
4 29
5 21
6 10
7 5
8 2
a. Compute the expected number of arrivals per minute.
b. Compute the standard deviation.