Question
$1.00 Need RES 341 Week 5 question
- From Mathematics: General-Mathematics
- Closed, but you can still post tutorials
- Due on Jul. 22, 2012
- Asked on Jul. 19, 2012 at 09:40:22AM
Q:
8.45
A random sample of 21 nickels measured with a very accurate micrometer showed a mean diameter
of 0.834343 inches with a standard deviation of 0.001886 inches. (a) Why would nickel
diameters vary? (b) Construct a 99 percent confidence interval for the true mean diameter of a
nickel. (c) Discuss any assumptions that are needed. (d) What sample size would ensure an error of
± 0.0005 inches with 99 percent confidence? (Data are from a project by MBA student Bob
Tindall.)
8.61
NBC asked a sample of VCR owners to record “Late Night with David Letterman” on their VCRs.
Of the 125 VCR owners surveyed, 83 either “gave up or screwed up” because they did not understand
how to program the VCR. (a) Construct a 90 percent confidence interval for the true proportion
of VCR owners who cannot program their VCRs. (b) Would viewers of this program be
typical of all television viewers? Explain. (Data are from Popular Science 237, no. 5, p. 63.)
$3.00
8.45 and 8.61 Sum correct solution with calculation all steps
- This tutorial hasn't been purchased yet.
- Posted on Jul. 19, 2012 at 10:27:05AM
A:
Preview: ... include normality of sampling distribution.
d)
set error equal to 0.0005 in original equation and solve for n
0.0005 = 2.845 X [.001886/(n^0.5)] n=115.22347 or 116
a)
Estimated p = 83 / 125 = 0.664
Variance of proportion = p*(1-p)/n
= 0.664(0.336)/125 =0.0017848
S.D. of p is sqrt[0.001785] = 0.0422
Confidence interval:
phat-zval*sd = 0.664 - (1.645)(0.042247) ...
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