(a) What is the sample mean years to maturity for corporate bonds and what is the sample standard deviation? X = yr yr = S (b) Develop a 95% confidence interval for the population mean years to maturity. yr to yr (c) What is the sample mean yield on corporate bonds and what is the sample standard deviation? X = % S = %

glucose levels in oatients free of diabetes are assumed to follow a normal distribution with a mean of 120 and a standard deviation of 16. What proportion of patients have glucose levels exceesing 115?

A random sample of 83 eighth grade students' scores on a national mathematics assessment test has a mean score of 275. This test result prompts a state school administrator to declare that the mean score for the state's eighth graders on this exam is more than 270. Assume that the population standard deviation is 30. At a = 0.02, is there enough evidence to support the administrator's claim? Complete parts (a) through (e). (a) Write the claim mathematically and identify Ho and H,. Choose the correct answer below. O A. Ho: H=270 (claim) Ha: u> 270 O B. Ho u2270 (claim) H µ 270 (claim) O E. H, µs270 (claim) Ha p>270 Ho Hs 270 H, p > 270 (claim) OF.

Arandom sample of 77 eighth grade students scores on a national mathematics assessment test has a mean score of 266. This test result prompts a state school administrator to declare that the mean score for the state's eighth graders on this exam is more than 260. Assume that the population standard deviation is 37. At a= 0.13, is there enough evidence to support the administrator's claim? Complete parts (a) through (e). (a) Write the claim mathematically and identify Hg and H,. Choose the correct answer below. OB. Hg u 260 D. Họ: us 260 H, > 260 (claim) O. H: u= 260 (claim) H, u> 260 OF. H: pa 260 (claim) H, p 260 (claim) (b) Find the standardized test statistic z, and ts corresponding area 2= 1.42 (Round to two decimal places as needed) (c) Find the P-value. Pvalue =D(Round to three decimal places as needed.)

Concerns about climate change and CO, reduction have initiated the commercial production of blends of biodiesel (e.g., from renewable sources) and petrodiesel (from fossil fuel). Random samples of 48 blended fuels are tested in a lab to ascertain the bio/total carbon ratio. (a) If the true mean is .9200 with a standard deviation of 0.0050, within what interval will 99 percent of the sample means fall? (Round your answers to 4 decimal places.) The interval is from to (b) If the true mean is .9200 with a standard deviation 2050, what is the sampling distribution of X ? 1. Exactly normal with u= 9200 and o =0.0050. 2. Approximately normal with u= .9200 and o = 0.0050. 3. Exactly normal with u= .9200 and o = 0.0050/V8. 4. Approximately normal with u= .9200 and o, = 0.0050/V48.