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Workshop 5 Group Review Questions
7.22
a.If you select samples of n=2, describe the shape of the sample distribution of Xbar.
b.If you select samples of n=100, describe the shape of the sample distribution of Xbar.
1.
Complete at least 6 problems (3 from each chapter)
with your team. Note: use Ex
is available for you to ask questions and to assist your peers with their questions:
a. Chapter 7: 7.22 through 7.26, 7.38, and 7.56.
b. Chapter 8: 8.32, 8.33, and 8.60 through 8.67.
2. Save your work and submit your team’s answers via Submit Assignments.
One stud
document in that submission what work each member of the team did on the assignmen
All work MUST be shown on the appropriate worksheet; Link each appropriate box to
Remember that your full work must be contained on the appropriate worksheet for full
The US Census Bureau announce that the median sales price of new houses sold in March 2006 was $22
sales price was $ 279,1000.
Assume that the standard deviation of the prices is $ 90,000
Xbar follows normal distribution with mean µ = 279,100 and standard distribution
Sigma/
SQRT(n) = 90,000/SQRT(2) = 63639.61031.
Xbar follows normal distribution with mean µ = 279,100 and standard distribution
Sigma/
SQRT(n) = 90,000/SQRT(100) = 9,000
c. If you select a random sample of n=100, what is the probability that the sample mean will be
less than $ 250,000?
250,000 279,100
P (X< 250,000) = P
= P (Z < 3.2333) = 0.0006118
9,000
X
n
μ
σ
 
<
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View Full Document7.23
a.what is the probability that the sample mean is between 7.8 and 8.2 minutes?
b.what is the probability that the sample mean is bettween 7.5 and 8.0 minutes?
7.24
a.what is the probability that the mean time spent per customer is at least 3 minutes?
b.there is an 85% chance that the sample mean is less than how many minutes?
c. What assumptions must you make in order to solve (a) and (b)?
Time spent using email per session is normally distributed with mu being 8 and sigma 2 minutes.
If you
of 25 sessions,
c. If you select a random sample of 100 sessions, what is the probability that the sample mean is
between 7.8 and 8.2 minutes?
d.
Explain the difference in the results of (a) and ©.c. If you select a random sample of n=1,
what is the probability that the sample mean will be less than $ 250,000?
The difference in the results is only because of the difference in sample size. As the sample size
changes, the standard error of sample mean (Sigma/SQRT(n)) also changes. In this case the
sample size increases from 25 to 100 and as a result the standard error of sample mean decreases
from 0.4 to 0.2. Because of this the zscores calculated in (c) has been increased from 0.5 to 1 and
thus the area between the zscores increased.
The amount of time a bank teller spends with each customer has a population mean of 3.10 minutes and
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 Spring '10
 Jeff
 Statistics

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