The number of arrivals per minute at a bank located in the central business dist
ID: 2923163 • Letter: T
Question
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 results shown in the table below. Complete parts a and b to the right.
Arrivals
Frequency
0
8
1
21
2
49
3
41
4
33
5
25
6
13
7
7
8
3
a. Compute the mean number of arrivals per minute.
muequals=nothing
(Type an integer or a decimal.)
b. Compute the standard deviation for the number of arrivals per minute.
sigmaequals=nothing
(Round to three decimal places as needed.)
Arrivals
Frequency
0
8
1
21
2
49
3
41
4
33
5
25
6
13
7
7
8
3
Explanation / Answer
a. Mean = (0*8 + 1*21 + 2*49 + 3*41 + 4*33 + 5*25 + 6*13 + 7*7 + 8*3)/200 = 650/200 = 3.25.
b. Variance = (0*8 + 1*21 + 4*49 + 9*41 + 16*33 + 25*25 + 36*13 + 49*7 + 64*3)/200 - 3.25*3.25 = 3.1475
Standard deviation = 3.1475 = 1.744.