According to a census company, 7.1% of all babies born are of low birth weight. An obstetrician wanted to know whether mothers between the ages of 35 and 39 years give birth to a higher percentage of low-birth-weight babies. She randomly selected 280 births for which the mother was 35 to 39 years old and found 31 low-birth-weight babies. Complete parts (a) through (c) below. (a) If the proportion of low-birth-weight babies for mothers in this age group is 0.071, compute the expected number of low-birth-weight births to 35- to 39-year-old mothers. What is the expected number of births to mothers 35 to 39 years old that are not low birth weight? The expected number of low-birth-weight births to 35- to 39-year-old mothers is 19.88 The expected number of births to mothers 35 to 39 years old that are not low birth weight is 260.12 (Type integers or decimals.) (b) Answer the obstetrician's question at the a = 0.10 level of significance using the chi-square goodness-of-fit test. State the null and alternative hypotheses for this test. Ho: p = 0.071 H1: p > 0.071 Use technology to compute the P-value for this test. Use the Tech Help button for further assistance. P-value = (Round to three decimal places as needed.) State a conclusion for this test in the context of the obstetrician's question. Choose the correct answer below. A. Reject the null hypothesis. There is sufficient evidence to conclude that mothers between the ages of 35 and 39 years give birth to a higher percentage of low-birth-weight babies at the a = 0.10 level of significance. B. Do not reject the null hypothesis. There is sufficient evidence to conclude that mothers between the ages of 35 and 39 years give birth to a higher percentage of low-birth-weight babies at the a = 0.10 level of significance. C. Do not reject the null hypothesis. There is not sufficient evidence to conclude that mothers between the ages of 35 and 39 years give birth to a higher percentage of low-birth-weight babies at the a = 0.10 level of significance. D. Reject the null hypothesis. There is not sufficient evidence to conclude that mothers between the ages of 35 and 39 years give birth to a higher percentage of low-birth-weight babies at the a = 0.10 level of significance. (c) Answer the obstetrician's question at the a = 0.10 level of significance using a z-test for a population proportion. State the null and alternative hypotheses for this test. Ho: = 0.071 H1: p 0.071 Use technology to compute the P-value for this test. Use the Tech Help button for further assistance. P-value = (Round to three decimal places as needed.) %3D State a conclusion for this test in the context of the obstetrician's question. Choose the correct answer below. A. Reject the null hypothesis. There is sufficient evidence to conclude that mothers between the ages of 35 and 39 years give birth to a higher percentage of low-birth-weight babies at the a = 0.10 level of significance. B. Reject the null hypothesis. There is not sufficient evidence to conclude that mothers between the ages of 35 and 39 years give birth to a higher percentage of low-birth-weight babies at the a =0.10 level of significance. C. Do not reject the null hypothesis. There is not sufficient evidence to conclude that mothers between the ages of 35 and 39 years give birth to a higher percentage of low-birth-weight babies at the a = 0.10 level of significance. D. Do not reject the null hypothesis. There is sufficient evidence to conclude that mothers between the ages of 35 and 39 years give birth to a higher percentage of low-birth-weight babies at the a = 0.10 level of significance.

A researcher is analyzing regional differences in family size. She has information on the number of children for samples of families from four different regions. Which statistical test should she conduct?

Thirty-three percent of all Americans drink bottled water more than once a week (Natural resources Defense Council, December 4, 2015). Suppose you have been hired by the Natural Resources Defence Council to investigate bottled water consumption in St. Paul. You plan to select a sample of St. Paulites to estimate the proportion who drink bottled water more than once a week. Assume the popluation proportion of St. Paulites who drink bottled water more than once a week is 0.33 , the same as the overall proportion of Americans who drink bottled water more than once a week. Use z-table. b. Based upon a sample of  540 St. Paulites, what is the probability that the sample proportion will be within  of the population proportion (to 4 decimals). probability =_____ d. Based upon a smaller sample of only  200 St. Paulites, what is the probability that the sample proportion will be within 0.01 of the population proportion (to 4 decimals). probability=_____

In a study comparing banks in Germany and Great Britain, a sample of 145 matched pairs of banks was formed. Each pair contained one bank from Germany and one from Great Britain. The pairings were made in such a way that the two members were as similar as possible in regard to such factors as size and age. The ratio of total loans outstanding to total assets was calculated for each of the banks. For this ratio, the sample mean difference (German – Great Britain) was 0.0518, and the sample standard deviation of the differences was 0.3055. Test, against a two-sided alternative, the null hypothesis that the two population means are equal at α=0,05.

According to an article in Newsweek, the natural ratio of girls to boys is 100:105. In China, the birth ratio is 100:114 (46.7% girls). Suppose you don't believe the reported figures of the percent of girls born in China. You conduct a study. In this study, you count the number of girls and boys born in 150 randomly chosen recent births. There are 64 girls and 86 boys born of the 150. Based on your study, do you believe that the percent of girls born in China is 46.7? Conduct a hypothesis test at the 5% level.Note: If you are using a Student's t-distribution for the problem, you may assume that the underlying population is normally distributed. (In general, you must first prove that assumption, though.)State the distribution to use for the test. (Round your standard deviation to four decimal places.)P' ~     What is the test statistic? (Round your answer to two decimal places.)     What is the p-value? (Round your answer to four decimal places.) Construct a 95% confidence interval…

Suppose an internet marketing company wants to determine the percentage of customers who click on ads on their smartphones. How many customers should the company survey in order to be 94% confident that the estimated proportion is within 5% of the population proportion of customers who click on ads on their smartphones?

Suppose you have the following information on whether households have a landline phone or not, broken down by age of “Household Heads.”  A sample of 500 households was drawn in each of two communities (a) What is the overall (or “crude”) proportion of households in Community A that had a landline phone?  What is the corresponding proportion in Community B?    (b) What is the set of age-specific household landline rates for each community – that is, the rate within each age of household head category (<35 and 35+ hours, separately) for each community (A vs. B)?     (c) Please compare the age-specific landline rates of Community A vs. Community B and then compare the overall rates of the two communities.  Please “make sense” of the two different stories that these two measures imply.  Put differently, please “weave” these different results into one explanation that helps us understand landline use rates in these two communities.

A company studied the number of lost-time accidents occurring at its Brownsville, Texas, plant. Historical records show that 6% of the employees suffered lost-time accidents last year. Management believes that a special safety program will reduce such accidents to 4% during the current year. In addition, it estimates that 15% of employees who had lost-time accidents last year will experience a lost-time accident during the current year. a. What percentage of the employees will experience lost-time accidents in both years (to 2 decimals)? % b. What percentage of the employees will suffer at least one lost-time accident over the two-year period (to 2 decimals)? %

Thirty-two percent of all Americans drink bottled water more than once a week (Natural resources Defense Council, December 4, 2015). Supposeyou have been hired by the Natural Resources Defence Council to investigate bottled water consumption in St. Paul. You plan to select a sampleof St. Paulites to estimate the proportion who drink bottled water more than once a week. Assume the popluation proportion of St. Paulites whodrink bottled water more than once a week is 0.32, the same as the overall proportion of Americans who drink bottled water more than once aweek. Use z-table.a. Suppose you select a sample of 540 St. Paulites. Show the sampling distribution of ē (to 4 decimals).E) .32Op =.0201b. Based upon a sample of 540 St. Paulites, what is the probability that the sample proportion will be within 0.01 of the population proportion (to4 decimals).probability = C. Suppose you select a sample of 250 St. Paulites. Show the sampling distribution of ē (to 4 decimals).E(P) = 0.32Op = d.…

A company studied the number of lost-time accidents occurring at its Brownsville, Texas, plant. Historical records show that 7% of the employees suffered lost- time accidents last year. Management believes that a special safety program will reduce such accidents to 5% during the current year. In addition, it estimates that 15% of employees who had lost-time accidents last year will experience a lost-time accident during the current year. a. What percentage of the employees will experience lost-time accidents in both years (to 2 decimals)? % b. What percentage of the employees will suffer at least one lost-time accident over the two-year period (to 2 decimals)? %