Unit 6 Exercise
By:
Maryam Mohammad Amin
Due Date:
February 19th
, 2018
Course Code:
BUSI 1033 (
Statistics for Business)
Professor:
Dr. Albert Wong

1.
Assume that data contained in the
BUSI1013-Numerical Data A.xls
file is from a simple random
sample of customers of a Canadian retailer. Use this data to answer the following: (
4 points
)
a.
Develop a point estimate of the mean number of transactions for the retailer.
Number of transaction
Number of
Transactions
19
32
38
45
37
46
39
42
47
34
38
40
49
38
42
79
36
41
34
36
35
39
54
75
38
40
48
80
37
40
Total
1298
Point estimate of the mean number of transaction for the retailer is sample mean. Since E (sample mean)=
Population mean
X=
1298
30

X= 43.27
b.
Develop a point estimate of the population standard deviation of the number of transactions.
√
∑
(
x
−
x
)
2
n
−
1
= 13.34
2.
The average waiting time for customers at a fast food restaurant is 3.4 minutes. The population
standard deviation is 2.5 minutes. (
6 points
)
a.
Assume that the waiting time of customers at this restaurant follow a normal distribution,
what is the probability that a simple random sample of 50 customers will have a sample waiting
time of less than 3 minutes?
Given:
µ= 3.4
¿
2.5
n= 50
E(x)=µ: SD(x)=
❑
√
n
=
2.5
√
50
= 0.35
P(x<3)=P (
z
<−
¿
x
−
E
(
x
)
SD
(
x
)
<
3
−
3.4
0.35
=
P
¿
1.32)=0.043
b.
Do we need to make any assumption about the distribution of waiting times for the
calculation in Part a? Why or why not?
This sample mean follows normal distribution because the sample is taken random and the population
distribution is normal and the population standard deviation is known
c.
What is the probability that a simple random sample of 100 customers will have a sample
waiting time of less than 3 minutes?

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