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Sample Variability And Statistical Inferences Essay

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¶ … digit integers {1, 3, 5, 7, 9}. Sampling distribution of each sample is .04

Mean () Probability P (x)

If a population has a standard deviation ? of 25 units, what is the standard error of the mean if samples of size 16 are selected? Samples of size 36? Samples of size 100?

Standard error for sample size 16 25 / 4= 6.25

Standard error for sample size 36 25/6= 4.17

Standard error for sample size 100 25/10= 2.5

According to Nielsen's Television Audience report, in 2009 the average American home had 2.86 television sets (more than the average number of people per household, at 2.5 people). If the standard deviation for the number of televisions in a U.S. household is 1.2 and a random sample of 80 U.S. households is selected, the mean of this sample belongs to a sampling distribution.

a.What is the shape of this sampling distribution? Normal

b.What is the mean of this sampling distribution?

What is the standard deviation of this sampling distribution? .134

7.18

Consider a normal population with ? = 43 and ? = 5.2. Calculate the z-score for an x of 46.5 from a sample of size 16.

z= 46.5-43 / (5.2 / 4) = 3.5/1.3= 2.69

7.20

What is the probability that the sample of kindergarten children (pages 146-147) has a mean...

Using a sample of 100 students, the probability z score is
39.75- 39 / (2/10)= 3.75, and the probability from the table is .999

Unit 6

8.2 A because the results are clustered with low variation.

8.14

A sample of 60 night-school students' ages is obtained in order to estimate the mean age of night-school students. 25.3 years. The population variance is 16.

a.Give a point estimate for ?. 25.3

b.

25.3 ± 1.96(4/?60) and the 95% confidence interval is

24.29 < µ < 25.31

c.Find the 99% confidence interval for ?.

25.3 ± 2.58(4/?60) and the 95% confidence interval is

25.13 < µ < 25.47

8.24 A supplier of highway construction materials claims he can supply an asphalt mixture that will make roads that are paved with his materials less slippery when wet. A general contractor who builds roads wishes to test the supplier's claim. The null hypothesis is "Roads paved with this asphalt mixture are no less slippery than roads paved with other asphalt." The alternative hypothesis is "Roads paved with this asphalt mixture are less slippery than roads paved with other asphalt."

a.Describe the meaning…

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8.39

From candy to jewelry to flowers, the average consumer was expected to spend $123.89 for Mother's Day 2009, according to an April 2009 National Retail Federation survey. Local merchants felt this average was too high for their area. They contracted an agency to conduct a study. A random sample of 60 consumers was taken at a local shopping mall the Saturday before Mother's Day and produced a sample mean amount of $106.27. If ? = $39.50, does the sample provide sufficient evidence to support the merchants' claim at the 0.05 level of significance?

Z star is .0575, which means the p value is .48 and is not smaller than the established level of significance. Therefore, the sample does provide sufficient evidence to support the merchants' claims.
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