E-Text

E-Text
DAinsley T. Smith
RES/342
August 28, 2011
Walt Deckert

E-Text Chapter Exercise
Exercise: 8.48
A consider of 20 pages was taken without replacement from the 1,591-page phone directory Ameritech Pages Plus jaundiced Pages. On each page, the mean ara devoted to demonstrate ads was measured (a display as is a large draw a blank of multicolored illustrations, maps, and text). The data (in squ ar millimeters) are shown below:
02603564035360268369428536
268396469536162338403536536130
(a) Construct a 95 percent trustfulness interval for the true mean. (b)Why might normality be an core here? (c) What sample size would be needed to chance an error of ±10 square millimeters with 99 percent authority? (d) If this is not a reasonable requirement, suggest one that is. (Data are from a project by MBA student Daniel R. Dalach.)
A.
As the race variance is understood and the test magnitude is smaller, I wll give the t-distribution. Excel Megastat computations are as below:

95%| corporate trust level|
346.5| mean|
170.38| standardised. deviation.|
20| n|
2.093| t (df = 19)|
79.740| half-width|
426.240| upper confidence limit|
266.760| discredit confidence limit|

So, a 95 % assurance interval is between 266.760 and 426.240.

B.





Normality could be a problem because there are extreme figures (0s) in the facts set. This will impact the precision of the assurance intervals.

C.

As we dont have the measurements and sample magnitude, I will choose the z-distribution. Excel Megastat computations are listed below:

99%| confidence level|
346.50| mean|
170.38| std. dev.|
20| n|
2.576| z|
98.134| half-width|
444.634| upper confidence limit|
248.366| lower confidence limit|


With a confidence interval of 99 %, the z-score is 2.576. An effective method to get our answer is:
(z-value X standard deviation/10)2
(2.576 X 170.38/10)2 =...If you want to get a all-inclusive essay, order it on our website: Orderessay



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