In the airline business, "on-time" flight arrival is important for connecting flights and general customer satisfaction. Is there a difference between summer and winter average on-time flight arrivals? Let  x1  be a random variable that represents percentage of on-time arrivals at major airports in the summer. Let  x2  be a random variable that represents percentage of on-time arrivals at major airports in the winter. A random sample of  n1 = 16  major airports showed that  x1 = 74.2%,  with  s1 = 5.1%.  A random sample of  n2 = 18  major airports showed that  x2 = 69.7%,  with  s2 = 8.5%.  Note: For degrees of freedom d.f. not in the Student's t table, use the closest d.f. that is smaller. In some situations, this choice of d.f. may increase the P-value a small amount and thereby produce a slightly more "conservative" answer. (a) Does this information indicate a difference (either way) in the population mean percentage of on-time arrivals for summer compared to winter? Use  α = 0.05. (i) What is the level of significance?   What is the value of the sample test statistic? (Round your answer to three decimal places.) (b) Find a 95% confidence interval for  μ1 − μ2.  (Round your answers to two decimal places.) lower limit      % upper limit      %

Nationally, about 11% of the total U.S. wheat crop is destroyed each year by hail.† An insurance company is studying wheat hail damage claims in a county in Colorado. A random sample of 16 claims in the county reported the percentage of their wheat lost to hail. 16 6 8 9 10 18 14 13 9 10 25 18 13 8 14 3 The sample mean is x = 12.1%. Let x be a random variable that represents the percentage of wheat crop in that county lost to hail. Assume that x has a normal distribution and σ = 5.0%. Do these data indicate that the percentage of wheat crop lost to hail in that county is different (either way) from the national mean of 11%? Use ? = 0.01. (a) What is the level of significance?   Compute the z value of the sample test statistic. (Round your answer to two decimal places.)(c) Find (or estimate) the P-value. (Round your answer to four decimal places.)

It has been found that 25.1% of men (Group 1) 20 years and older suffer from hypertension (high blood pressure) and 33.9% of women (Group 2) are hypertensive. A random sample of 164 of each gender was selected from recent hospital records, and the following results were obtained. Can you conclude that a higher percentage of women have high blood pressure? Use =0.05. Men: 42 patients had high blood pressure Women: 52 patients had high blood pressure   Required: Test Value Only the final answer should be rounded-off to TWO decimal places.

Describe a study in which you can use both nonparametric and parametric statistics. A researcher has participants expecting to receive either painful or mild electrical shocks during a study wait in a quarter-full waiting room with other participants. He then measures whether they choose to sit next to other participants or if they sit far away on their own. What is the best test to run for this study and why?

Imagine that a researcher wants to compare the intelligence levels of Poodles to all dogs.  He hypothesizes that Poodles will score differently than other dogs.  He uses a standard test of dog intelligence in his study. The population of all dogs has a mean of μ = 100, and an SD of 15.  He obtains a random sample of 500 Poodles and he finds that the mean intelligence score of the sample is 117.   Is this a one- or two- tailed test? Write the Ho and Ha for this research question. What kind of statistic should be calculated to test the hypothesis? Compute that statistic by hand What should the researcher conclude? Write a blurb describing the results

ASK YOUR TEACHER Nationally, about 11% of the total U.S. wheat crop is destroyed each year by hail.t An insurance company is studying wheat hail damage claims in a county in Colorado. A random sample of 16 claims in the county reported the percentage of their wheat lost to hail. 14 7 10 11 12 19 14 11 9 8 23 19 13 7 10 7 The sample mean is x = 12.1%. Let x be a random variable that represents the percentage of wheat crop in that county lost to hail. Assume that x has a normal distribution and a = 5.0%. Do these data indicate that the percentage of wheat crop lost to hail in that county is different (either way) from the national mean of 11%? Use a = 0.01. (a) What is the level of significance? State the null and alternate hypotheses. Will you use a left-tailed, right-tailed, or two-tailed test? O Ho: H = 11%; H,: µ 11%; right-tailed O Ho: H + 11%; H,: u = 11%; two-tailed O Ho: H = 11%; H,: u + 11%; two-tailed (b) What sampling distribution will you use? Explain the rationale for your…

Is the difference between the mean annual salaries of statisticians in Region 1 and Region 2 more than $5000? To decide, you select a random sample of statisticians from each region. The results of each survey are shown to the right. At a = 0.10, what should you conclude? Region 1 X1 = $67,700 Region 2 X2 = $62,000 01 = $8825 02 = $9025 n1 = 48 n2 = 43 Click here to view page 1 of the standard normal distribution table. Click here to view page 2 of the standard normal distribution table. ..... Choose the correct null and alternative hypotheses below. B. Ho: H1- H2 O C. Ho: H1 -H2 > 5000 Ha: H1 - H2 55000 O A. Ho: H1 - H2 > 5000 + 5000 Ha: H1 - H2 2 5000 Ha: H1 - H2 = 5000 O E. Ho: H1 - H2 2 5000 O D. Ho: H1 - H2 = 5000 Ha: H1 - H2 # 5000 F. Ho: µ1 - H2 5 5000 Ha: H1 - H2 > 5000 Ha: H1 - H2 В. Z

Child Health and Development Studies (CHDS) has been collecting data about expectant mothers in Oakland, CA since 1959. One of the measurements taken by CHDS is the weight increase (in pounds) for expectant mothers in the second trimester. In a fictitious study, suppose that CHDS finds the average weight increase in the second trimester is 14 pounds. Suppose also that, in 2015, a random sample of 40 expectant mothers have mean weight increase of 15.8 pounds in the second trimester, with a standard deviation of 6.2 pounds. A hypothesis test is done to see if there is evidence that weight increase in the second trimester is greater than 14 pounds. Find the p-value for the hypothesis test.  The p-value should be rounded to 4 decimal places.

A transect is an archaeological study area that is 1/5 mile wide and 1 mile long. A site in a transect is the location of a significant archaeological find. Let x represent the number of sites per transect. In a section of Chaco Canyon, a large number of transects showed that x has a population variance ?2 = 42.3. In a different section of Chaco Canyon, a random sample of 19 transects gave a sample variance s2 = 46.9 for the number of sites per transect. Use a 5% level of significance to test the claim that the variance in the new section is greater than 42.3. Find a 95% confidence interval for the population variance. (b) Find the value of the chi-square statistic for the sample. (Round your answer to two decimal places.)- 19.96 What are the degrees of freedom? -18 (c) Find or estimate the P-value of the sample test statistic. P-value > 0.1000.050 < P-value < 0.100    0.025 < P-value < 0.0500.010 < P-value < 0.0250.005 < P-value < 0.010P-value < 0.005…

Executives of a supermarket chain are interested in the amount of time that customers spend in the stores during shopping trips. The mean shopping time,  μ , spent by customers at the supermarkets has been reported to be  36  minutes, but executives hire a statistical consultant and ask her to determine whether it can be concluded that  μ  is greater than  36  minutes. The consultant plans to do a statistical test and collects a random sample of  50  shopping times at the supermarkets. Suppose that the population of shopping times at the supermarkets has a standard deviation of  16  minutes and that the consultant performs her hypothesis test using the  0.05  level of significance.