University of Irvine Standard Deviation Statistics Questions Show how you get the answer, type it. Thank you. I will Post excel you will need for homework

University of Irvine Standard Deviation Statistics Questions Show how you get the answer, type it. Thank you. I will Post excel you will need for homework questions 8.19). And the T table you will need for the homework Area or
probability Entries in the table give 1 values for an area
or probability in the upper tail of the
distribution. For example, with 10 degrees
of freedom and a .05 area in the upper tail
0
105 = 1.812.
1
Area in Upper Tail
Degrees
of Freedom
.20
.10
.05
.025
.01
.005
1
2
1.376
1.061
.978
.941
3.078
1.886
1.638
1.533
6.314
2.920
2.353
2.132
12.706
4.303
3.182
2.776
31.821
6.965
4.541
3.747
63.656
9.925
5.84)
4.604
4
5
6
7
8
9
.920
.906
.896
.889
.883
1.476
1.440
1.415
1.397
1.383
2.015
1.943
1.895
1.860
1.833
2.571
2.447
2.365
2.306
2.262
3.365
3.143
2.998
2.896
2.821
4.03
3.707
3.499
3.3555
3.250
10
11
12
13
14
.879
.876
.873
.870
.868
1.372
1.363
1.356
1.350
1.345
1.812
1.796
1.782
1.771
1.761
2.228
2.201
2.179
2.160
2.145
2.764
2.718
2.681
2.650
2.624
3.169
3.106
3.055
3.012
2.977
15
16
17
18
19
.866
.865
.863
.862
.861
1.341
1.337
1.333
1.330
1.328
1.753
1.746
1.740
1.734
1.729
2.131
2.120
2.110
2.101
2.093
2.602
2.583
2.567
2.552
2.539
2.947
2.921
2.898
2.878
2.861
20
21
22
23
24
.860
.859
.858
.858
.857
1.325
1.323
1.321
1.319
1.318
1.725
1.721
1.717
1.714
1.711
2.086
2.080
2.074
2.069
2.064
2.528
2.518
2.508
2.500
2.492
2.845
2.831
2.819
2.807
2.797
.856
.856
25
26
27
28
29
.855
.855
1.316
1.315
1.314
1.313
1.311
1.708
1.706
1.703
1.701
1.699
2.060
2.056
2.052
2.048
2.045
2.485
2.479
2.473
2.467
2.462
2.787
2.779
2.771
2.768
2.756
.854
30
31
32
33
34
.854
.853
.853
.853
.852
1.310
1.309
1.309
1.308
1.307
1.697
1.696
1.694
1.692
1.691
2.042
2.040
2.037
2.035
2.032
2.457
2.453
2.449
2.445
2.441
2.750
2.744
2.738
2.733
2.728
Meal Price ($)
22.78
33.89
22.77
18.04
23.29
35.28
42.38
36.88
38.55
41.68
25.73
34.19
31.75
25.24
26.32
19.57
36.57
32.97
36.83
30.17
37.29
25.37
24.71
28.79
32.83
43.00
35.23
34.76
33.06
27.73
31.89
38.47
39.42
40.72
43.92
36.51
45.25
33.51
29.17
30.54
26.74
37.93
BUSINESS STATISTICS (MGMT 7)
HOMEWORK 4
Instructor: Lingwen Huang
a.
c.
Chapter 8:
10. Costs are rising for all kinds of medical care. The mean monthly rent at assisted-living
facilities was reported to have increased 17% over the last five years to $3486 (The
Wall Street Journal, October 27, 2012). Assume this cost estimate is based on a sample
of 120 facilities and, from past studies, it can be assumed that the population standard
deviation is o = $650.
a. Develop a 90% confidence interval estimate of the population mean monthly rent.
b. Develop a 95% confidence interval estimate of the population mean monthly rent.
c. Develop a 99% confidence interval estimate of the population mean monthly rent.
d. What happens to the width of the confidence interval as the confidence level is
increased? Does this seem reasonable? Explain.
19. The mean cost of a meal for two in a mid-range restaurant in Tokyo is $40 (Numbeo.com
website, December 14, 2014). How do prices for comparable meals in Hong Kong
compare? The DATAfile Hong KongMeals contains the costs for a sample of 42 recent
meals for two in Hong Kong mid-range restaurants.
With 95% confidence, what is the margin of error?
b. What is the 95% confidence interval estimate of the population mean?
How do prices for meals for two in mid-range restaurants in Hong Kong compare to
prices for comparable meals in Tokyo restaurants?
29. Customers arrive at a movie theater at the advertised movie time only to find that they have
to sit through several previews and prepreview ads before the movie starts. Many complain
that the time devoted to previews is too long (The Wall Street Journal, October 12, 2012).
A preliminary sample conducted by The Wall Street Journal showed that the standard
deviation of the amount of time devoted to previews was 4 minutes. Use that as a planning
value for the standard deviation in answering the following questions.
a. If we want to estimate the population mean time for previews at movie theaters with a
margin of error of 75 seconds, what sample size should be used? Assume 95% confidence.
b. If we want to estimate the population mean time for previews at movie theaters with a
margin of error of 1 minute, what sample size should be used? Assume 95% confidence.
41. Fewer young people are driving. In 1983, 87% of 19-year-olds had a driver’s license.
Twenty-five years later that percentage had dropped to 75% (University of Michigan
Transportation Research Institute website, April 7, 2012). Suppose these results are based
on a random sample of 1200 19-year-olds in 1983 and again in 2008.
At 95% confidence, what is the margin of error and the interval estimate of the number
of 19-year-old drivers in 1983?
b. At 95% confidence, what is the margin of error and the interval estimate of the number
of 19-year-old drivers in 2008?
Is the margin of error the same in parts (a) and (b)? Why or why not?
a.
c.

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