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    Two-Sample Tests

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    I would like the response to the questions below in excel format, so that I can see the formulas used.

    10.11
    Digital cameras have taken over the majority of the point-and-shoot camera market. One of the important features of a camera is the battery life, as measured by the number of shots taken unit the battery needs to be recharged. The file DigitalCameras contains the battery life of 29 sub-compact cameras and 16 compact cameras (data extracted from "Digital Cameras," Consumer Reports, July 2009, pp. 28-29).
    Battery Life Camera Type Subcompact Compact
    320 Subcompact 320 520
    520 Subcompact 520 260
    160 Subcompact 160 400
    160 Subcompact 160 200
    300 Subcompact 300 300
    120 Subcompact 120 150
    520 Subcompact 520 360
    440 Subcompact 440 200
    300 Subcompact 300 260
    170 Subcompact 170 80
    150 Subcompact 150 200
    300 Subcompact 300 260
    180 Subcompact 180 400
    100 Subcompact 100 260
    150 Subcompact 150 200
    400 Subcompact 400
    170 Subcompact 170
    180 Subcompact 180
    160 Subcompact 160
    240 Subcompact 240
    320 Subcompact 320
    260 Subcompact 260
    150 Subcompact 150
    320 Subcompact 320
    180 Subcompact 180
    140 Subcompact 140
    220 Subcompact 220
    160 Subcompact 160
    340 Subcompact 340
    200 Subcompact 200
    130 Subcompact 130
    520 Compact
    260 Compact
    400 Compact
    200 Compact
    300 Compact
    150 Compact
    360 Compact
    200 Compact
    260 Compact
    80 Compact
    200 Compact
    260 Compact
    400 Compact
    260 Compact
    200 Compact

    a. Assuming that the population variances from both types of digital cameras are equal, is there evidence of a difference in the mean battery life between the two types of digital cameras (α=0.05)?
    Determine the p-value in (a) and interpret its meaning.
    b. Determine the p-value in (a) and interpret its meaning
    c. Assuming that the population variances from both types of digital cameras are equal, construct and interpret a 95% confidence interval estimate of the difference between the population mean battery life of the two types of digital cameras.
    10.21
    In industrial settings, alternative methods often exist for measuring variables of interest. The data in the file (coded to maintain confidentiality) represent measurements in-line that were collected from an analyzer during the production process and from an analytical lab (extracted from M. Leitnaker, "Comparing Measurement Processes: In-line Versus Analytical
    Measurements," Quality Engineering, 13, 2000-2001, pp. 293-298).
    Sample In-Line Analytical lab
    1 8.01 8.01
    2 7.56 7.29
    3 7.47 7.54
    4 7.4 7.42
    5 7.83 7.8
    6 7.5 7.65
    7 6.86 6.93
    8 7.31 7.46
    9 7.45 7.6
    10 7.23 7.4
    11 7.37 7.5
    12 7.49 7.41
    13 6.21 6.25
    14 6.68 6.54
    15 5.12 5.2
    16 4.84 4.7
    17 4.84 4.82
    18 5.21 5.33
    19 5.35 5.3
    20 5.6 5.4
    21 5.32 5.39
    22 5.16 5.17
    23 5.66 5.5
    24 6.31 6.24

    a. At the 0.05 level of significance, is there evidence of a difference in the mean measurements in-line and from and analytical lab?
    b. What assumption is necessary about the population distribution in order to perform this test?
    c. Use a graphical method to evaluate the validity of the assumption in (a).
    d. Construct and interpret a 95% confidence interval estimate of the difference in the mean measurements in-line and from an analytical lab.

    10.23
    In tough economic times, magazines and other media have trouble selling advertisements. Thus, one indicator of a weak economy is a reduction in the number of magazine pages devoted to advertisements. The file Ad Pages (attached) contains the number of pages devoted to advertisements in May 2008 and May 2009 for 12 men's magazines.

    a. At the 0.05 level of significance, is there evidence that the mean number of pages devoted to advertisements in men's magazines was higher in May 2008 than in May 2009?
    b. What assumption is necessary about the population distribution in order to perform this?
    c. Use a graphical method to evaluate the validity of the assumption in (b).
    d. Construct and interpret a 95% confidence interval estimate of the difference in the mean number of pages devoted to advertisements in men's magazines between May 2008 and May 2009.

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    Solution Summary

    Two-sample tests for digital camera majorities are determined. Population variances for both types of digital cameras are given.

    $2.19