A simple random sample of size n is drawn. The sample mean, x, is found to be 18.4, and the sample standard deviation, s, is found to be 4.5. Click the icon to view the table of areas under the t-distribution. (a) Construct a 95% confidence interval about u if the sample size, n, is 35. Lower bound: ; Upper bound: (Use ascending order. Round to two decimal places as needed.) (b) Construct a 95% confidence interval about u if the sample size, n, is 61. Lower bound:; Upper bound: (Use ascending order. Round to two decimal places as needed.) How does increasing the sample size affect the margin of error, E?

MATLAB: An Introduction with Applications
6th Edition
ISBN:9781119256830
Author:Amos Gilat
Publisher:Amos Gilat
Chapter1: Starting With Matlab
Section: Chapter Questions
Problem 1P
Question

10

A simple random sample of size n is drawn. The sample mean, x, is found to be 18.4, and the sample standard deviation, s, is found to be 4.5.
Click the icon to view the table of areas under the t-distribution.
(a) Construct a 95% confidence interval about u if the sample size, n, is 35.
Lower bound: ; Upper bound:
(Use ascending order. Round to two decimal places as needed.)
(b) Construct a 95% confidence interval about u if the sample size, n, is 61.
Lower bound: ; Upper bound:
(Use ascending order. Round to two decimal places as needed.)
How does increasing the sample size affect the margin of error, E?
A. The margin of error does not change.
B. The margin of error increases.
O c. The margin of error decreases.
(c) Construct a 99% confidence interval about u if the sample size, n, is 35.
Lower bound: ; Upper bound:
(Use ascending order. Round to two decimal places as needed.)
Compare the results to those obtained in part (a). How does increasing the level of confidence affect the size of the margin of error,
E?
O A. The margin of error decreases.
B. The margin of error increases.
O C. The margin of error does not change.
(d) If the sample size is 16, what conditions must be satisfied to compute the confidence interval?
O A. The sample must come from a population that is normally distributed and the sample size must be large.
O B. The sample size must be large and the sample should not have any outliers.
C. The sample data must come from a population that is normally distributed with no outliers.
Transcribed Image Text:A simple random sample of size n is drawn. The sample mean, x, is found to be 18.4, and the sample standard deviation, s, is found to be 4.5. Click the icon to view the table of areas under the t-distribution. (a) Construct a 95% confidence interval about u if the sample size, n, is 35. Lower bound: ; Upper bound: (Use ascending order. Round to two decimal places as needed.) (b) Construct a 95% confidence interval about u if the sample size, n, is 61. Lower bound: ; Upper bound: (Use ascending order. Round to two decimal places as needed.) How does increasing the sample size affect the margin of error, E? A. The margin of error does not change. B. The margin of error increases. O c. The margin of error decreases. (c) Construct a 99% confidence interval about u if the sample size, n, is 35. Lower bound: ; Upper bound: (Use ascending order. Round to two decimal places as needed.) Compare the results to those obtained in part (a). How does increasing the level of confidence affect the size of the margin of error, E? O A. The margin of error decreases. B. The margin of error increases. O C. The margin of error does not change. (d) If the sample size is 16, what conditions must be satisfied to compute the confidence interval? O A. The sample must come from a population that is normally distributed and the sample size must be large. O B. The sample size must be large and the sample should not have any outliers. C. The sample data must come from a population that is normally distributed with no outliers.
Area in
right tail
Table VI
t-Distribution
Area in Right Tail
df
0.25
0.20
0.15
0.10
0.05
0.025
0.02
0.01
0.005
0.0025
0.001
0.0005
127.321
1.000
0.816
3
1.963
1.386
3.078
1.886
1.638
1.533
1.476
6.314
2.920
2.353
2.132
2.015
12.706
15.894
4.849
31.821
318.309
22.327
636.619
31.599
12.924
8.610
6.869
1.376
63.657
4.303
3.182
2.776
2.571
9.925
5,841
4.604
2
1.061
0.978
0.941
0.920
6.965
14.089
7.453
5.598
4.773
0.765
0.741
3.482
2.999
2.757
1.250
4,541
1.190
1.156
3.747
3.365
10.215
7.173
5.893
0.727
4.032
1.134
1.119
1.440
1.415
1.397
1.383
1.372
2.447
2.365
2.306
2.262
2.228
0.906
0.896
5.959
5.408
1.943
1.895
1.860
1.833
1.812
2.612
2.517
3.143
2.998
2.896
2.821
2.764
3.707
3.499
3.355
3.250
3.169
4.317
4.029
3.833
3.690
3.581
0.718
0.711
5.208
4.785
7
0.889
0.883
8
0.706
1.108
2.449
4.501
4.297
5.041
0.703
1.100
1.093
9
2.398
4.781
10
0.700
0.879
2.359
4.144
4.587
0.876
0.873
1.363
1.356
1.350
1.345
1.341
2.201
2.179
11
12
13
2.328
2.303
2.282
2.264
2.249
2.718
2.681
2.650
2.624
2.602
3.106
3.055
3.012
2.977
3.497
3.428
3.372
3.326
3.286
4.025
3.930
3.852
3.787
3.733
0.697
4.437
4.318
4.221
4.140
4.073
1.088
1.796
1.083
1.782
1.771
1.761
1.753
0.695
0.694
0.870
1.079
2.160
0.692
0.691
0.868
0.866
2.145
2.131
14
1.076
15
1.074
2.947
2.120
2.110
2.101
2.093
2.086
3.252
3.222
3.197
3.174
3.153
16
0.690
0.865
1.071
1.337
1.333
1.330
1.328
1.325
1.746
2.235
2.224
2.214
2.205
2.197
2.583
2.567
2.552
2.539
2.528
2.921
3.686
0.689
0.688
0.688
0.687
1.069
1.067
1.066
1.064
1.740
1.734
1.729
1.725
2,898
2.878
2.861
2.845
3.646
3.610
3.579
3.552
4.015
3.965
3.922
3.883
3.850
17
0.863
0.862
0.861
0.860
18
19
20
0.686
0.859
0.858
0.858
0.857
0.856
1.063
1.061
1.060
1.059
1.058
1.721
1.717
1.714
1.711
1.708
2.518
2.508
2.500
2.492
2.485
2.831
2.819
2.807
2.797
2.787
3.135
3.119
3.527
3.505
3.485
3.467
3.450
21
1.323
2.080
2.189
2.183
2.177
2.172
2.167
3.819
3.792
3.768
3.745
3.725
1.321
2.074
2.069
2.064
2.060
22
0.686
23
0.685
0.685
0.684
1.319
1.318
1.316
3.104
3.091
24
25
3.078
26
27
28
29
30
0.684
0.684
0.683
0.683
0.683
0.856
0.855
0.855
0.854
0.854
1.058
1.057
1.056
1.055
1.055
1.706
1.703
1.701
1.699
1.697
2.056
2.052
2.048
2.045
2.042
2.162
2.158
2.154
2.150
2.147
2.479
2.473
2.467
2.462
2.457
2.779
2.771
2.763
2.756
2.750
3.067
3.057
3.047
3.038
3.030
3.435
3.421
3.408
3.396
3.385
3.707
3.690
3.674
3.659
3.646
1.315
1.314
1.313
1.311
1.310
0.682
0.682
0.682
0.853
0.853
1.054
1.054
1.053
1.052
1.052
1.696
1.694
1.692
1.691
1.690
2.040
2.037
2.035
2.032
2.030
2.453
2.449
31
32
33
34
35
0.853
0.852
0.852
1.309
1.309
1.308
1.307
1.306
2.144
2.141
2.138
2.136
2.133
2.445
2.441
2.438
2.744
2.738
2.733
2.728
2.724
3.022
3.015
3.008
3.002
2.996
3.375
3.365
3.356
3.348
3.340
3.633
3.622
3.611
0.682
3.601
0.682
3.591
0.852
0.851
0.851
0.851
0.851
1.052
1.051
1.051
1.050
1.050
1.688
1.687
1.686
1.685
1.684
2.434
2.431
2.429
3.333
3.326
3.319
3.313
3.307
36
0.681
0.681
0.681
0.681
0.681
1.306
1.305
1.304
1.304
1.303
2.028
2.026
2.024
2.023
2.021
2.131
2.129
2.127
2.719
2.715
2.712
2.708
2.704
2.990
3.582
37
38
39
2.985
2.980
2.976
2.971
3.574
3.566
2.125
2.123
2.426
3.558
40
2.423
3.551
0.679
0.679
1.047
1.045
1.044
1.043
2.009
2.000
1.994
1.990
2.678
2.660
2.648
2.639
2.109
2.099
2.937
2.915
3.261
3.232
50
0.849
0.848
0.847
0.846
1.299
1.296
1.676
1.671
1.667
1.664
2.403
2.390
2.381
2.374
3.496
3.460
3.435
3.416
60
2.093
2.088
3.211
3.195
70
0.678
0.678
1.294
1.292
2.899
80
2.887
Transcribed Image Text:Area in right tail Table VI t-Distribution Area in Right Tail df 0.25 0.20 0.15 0.10 0.05 0.025 0.02 0.01 0.005 0.0025 0.001 0.0005 127.321 1.000 0.816 3 1.963 1.386 3.078 1.886 1.638 1.533 1.476 6.314 2.920 2.353 2.132 2.015 12.706 15.894 4.849 31.821 318.309 22.327 636.619 31.599 12.924 8.610 6.869 1.376 63.657 4.303 3.182 2.776 2.571 9.925 5,841 4.604 2 1.061 0.978 0.941 0.920 6.965 14.089 7.453 5.598 4.773 0.765 0.741 3.482 2.999 2.757 1.250 4,541 1.190 1.156 3.747 3.365 10.215 7.173 5.893 0.727 4.032 1.134 1.119 1.440 1.415 1.397 1.383 1.372 2.447 2.365 2.306 2.262 2.228 0.906 0.896 5.959 5.408 1.943 1.895 1.860 1.833 1.812 2.612 2.517 3.143 2.998 2.896 2.821 2.764 3.707 3.499 3.355 3.250 3.169 4.317 4.029 3.833 3.690 3.581 0.718 0.711 5.208 4.785 7 0.889 0.883 8 0.706 1.108 2.449 4.501 4.297 5.041 0.703 1.100 1.093 9 2.398 4.781 10 0.700 0.879 2.359 4.144 4.587 0.876 0.873 1.363 1.356 1.350 1.345 1.341 2.201 2.179 11 12 13 2.328 2.303 2.282 2.264 2.249 2.718 2.681 2.650 2.624 2.602 3.106 3.055 3.012 2.977 3.497 3.428 3.372 3.326 3.286 4.025 3.930 3.852 3.787 3.733 0.697 4.437 4.318 4.221 4.140 4.073 1.088 1.796 1.083 1.782 1.771 1.761 1.753 0.695 0.694 0.870 1.079 2.160 0.692 0.691 0.868 0.866 2.145 2.131 14 1.076 15 1.074 2.947 2.120 2.110 2.101 2.093 2.086 3.252 3.222 3.197 3.174 3.153 16 0.690 0.865 1.071 1.337 1.333 1.330 1.328 1.325 1.746 2.235 2.224 2.214 2.205 2.197 2.583 2.567 2.552 2.539 2.528 2.921 3.686 0.689 0.688 0.688 0.687 1.069 1.067 1.066 1.064 1.740 1.734 1.729 1.725 2,898 2.878 2.861 2.845 3.646 3.610 3.579 3.552 4.015 3.965 3.922 3.883 3.850 17 0.863 0.862 0.861 0.860 18 19 20 0.686 0.859 0.858 0.858 0.857 0.856 1.063 1.061 1.060 1.059 1.058 1.721 1.717 1.714 1.711 1.708 2.518 2.508 2.500 2.492 2.485 2.831 2.819 2.807 2.797 2.787 3.135 3.119 3.527 3.505 3.485 3.467 3.450 21 1.323 2.080 2.189 2.183 2.177 2.172 2.167 3.819 3.792 3.768 3.745 3.725 1.321 2.074 2.069 2.064 2.060 22 0.686 23 0.685 0.685 0.684 1.319 1.318 1.316 3.104 3.091 24 25 3.078 26 27 28 29 30 0.684 0.684 0.683 0.683 0.683 0.856 0.855 0.855 0.854 0.854 1.058 1.057 1.056 1.055 1.055 1.706 1.703 1.701 1.699 1.697 2.056 2.052 2.048 2.045 2.042 2.162 2.158 2.154 2.150 2.147 2.479 2.473 2.467 2.462 2.457 2.779 2.771 2.763 2.756 2.750 3.067 3.057 3.047 3.038 3.030 3.435 3.421 3.408 3.396 3.385 3.707 3.690 3.674 3.659 3.646 1.315 1.314 1.313 1.311 1.310 0.682 0.682 0.682 0.853 0.853 1.054 1.054 1.053 1.052 1.052 1.696 1.694 1.692 1.691 1.690 2.040 2.037 2.035 2.032 2.030 2.453 2.449 31 32 33 34 35 0.853 0.852 0.852 1.309 1.309 1.308 1.307 1.306 2.144 2.141 2.138 2.136 2.133 2.445 2.441 2.438 2.744 2.738 2.733 2.728 2.724 3.022 3.015 3.008 3.002 2.996 3.375 3.365 3.356 3.348 3.340 3.633 3.622 3.611 0.682 3.601 0.682 3.591 0.852 0.851 0.851 0.851 0.851 1.052 1.051 1.051 1.050 1.050 1.688 1.687 1.686 1.685 1.684 2.434 2.431 2.429 3.333 3.326 3.319 3.313 3.307 36 0.681 0.681 0.681 0.681 0.681 1.306 1.305 1.304 1.304 1.303 2.028 2.026 2.024 2.023 2.021 2.131 2.129 2.127 2.719 2.715 2.712 2.708 2.704 2.990 3.582 37 38 39 2.985 2.980 2.976 2.971 3.574 3.566 2.125 2.123 2.426 3.558 40 2.423 3.551 0.679 0.679 1.047 1.045 1.044 1.043 2.009 2.000 1.994 1.990 2.678 2.660 2.648 2.639 2.109 2.099 2.937 2.915 3.261 3.232 50 0.849 0.848 0.847 0.846 1.299 1.296 1.676 1.671 1.667 1.664 2.403 2.390 2.381 2.374 3.496 3.460 3.435 3.416 60 2.093 2.088 3.211 3.195 70 0.678 0.678 1.294 1.292 2.899 80 2.887
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