A scientist has read that the mean birth weight of babies born at full term is 7.3 pounds. The scientist has good reason to believe that the mean birth weight of babies born at full term, μ, is less than this value and plans to perform a statistical test. She selects a random sample of birth weights of babies born at full term and finds the mean of the sample to be 6.9 pounds and the standard deviation to be 1.7 pounds. Based on this information, complete the parts below. (a) What are the null hypothesis H and the alternative hypothesis H₁ that should be used for the test? Ho :O H₁:0 (b) Suppose that the scientist decides not to reject the null hypothesis. What sort of error might she be making? (Choose one) ▼ (c) Suppose the true mean birth weight of babies born at full term is 7.3 pounds. Fill in the blanks to describe a Type I error. A Type I error would be (Choose one) the hypothesis that u is (Choose one) (Choose one) when, in fact, μ is (Choose one) H O

Loretta, who turns 91 this year, has heard that the mean systolic blood pressure among the elderly is 120 millimeters of mercury (mm Hg), but she believes that the actual value is higher. She bases her belief on a recently reported study of 19 randomly selected, elderly adults. The sample mean systolic blood pressure of the adults in the study was 121 mm Hg , and the sample standard deviation was 20 mm Hg. Assume that the population of systolic blood pressures of elderly adults is normally distributed. Based on the study, at the 0.1 level of significance, can it be concluded that μ , the mean systolic blood pressure among elderly adults, is greater than 120 mm Hg? Perform a one-tailed test. Then complete the parts below. Carry your intermediate computations to three or more decimal places and round your answers as specified in the table. (a) State the null hypothesis H0? and the alternative hypothesis H1? . H0:? H1:? (b) Determine the type of test statistic to…

In a school district, all sixth grade students take the same standardized test. The superintendant of the school district takes a random sample of 3030 scores from all of the students who took the test. She sees that the mean score is 169169 with a standard deviation of 7.06747.0674. The superintendant wants to know if the standard deviation has changed this year. Previously, the population standard deviation was 1313. Is there evidence that the standard deviation of test scores has decreased at the α=0.005α=0.005 level? Assume the population is normally distributed. Step 1 of 5:  State the null and alternative hypotheses. Round to four decimal places when necessary. Step 2 of 5:  Determine the critical value(s) of the test statistic. If the test is two-tailed, separate the values with a comma. Round your answer to three decimal places.     Step 3 of 5:  Determine the value of the test statistic. Round your answer to three decimal places. Step 4 of 5:  Make the…

In 2006, the Arundel County Maryland Department of Health tested local wells for elevated levels of arsenic. They found that 35 out of 71 wells showed elevated levels. Atomic  Absorption Spectroscopy is a very convenient way to measure arsenic in water. Imagine you are a lab manager and you have given identical arsenic samples (n = 10) to two different technicians. The first technician determines his sample has a standard deviation of 0.015 while the second technician reports a standard deviation of 0.033.  Construct a 90% confidence interval for the ratio of the sample standard deviations. Assume the population source data is normally distributed. Enter your answer using interval notation.

For college-bound seniors in 2018, SAT math scores are normally distributed with a mean of 515 and a standard deviation of 116. You suspect that seniors in the Auraria Campus are much brighter than the country as a whole, so you decide to conduct a test. In a random sample of 25 seniors, you find the mean SAT math score to be 555. You assume that the standard deviation of math scores in Auraria Campus are the same as the national standard deviation of a = 116. Is this sufficient evidence to conclude that Auraria Campus seniors are smarter? Take a -0.05.

Two chemical companies can supply a raw material. The concentration of a particular element in this material is important. The mean concentration for both suppliers is the same, but you suspect that the variability in concentration may differ for the two companies. The standard deviation of concentration in a random sample of n₁ = 10 batches produced by company 1 is s₁ = 4.7 grams per liter, and for company 2, a random sample of n₂ = 16 batches yield s₂ = 5.8 grams per liter. Is there sufficient evidence to conclude that the two populations variances differ? Use a = 0.05. a. Because 0.321 < 0.657 <3.77, fail to reject the null hypothesis b. Because 0.265 < 0.657 <3.12, fail to reject the null hypothesis c. Because 0.386 < 0.657 <3.01, fail to reject the null hypothesis d. None among the choices

Deanna is the principal at a Midwestern middle school and wants to know the average IQ of all female, seventh grade students.  She does not know anything about what the population distribution looks like.  She took a simple random sample of 31 seventh-grade girls in her school and found the average IQ score in her sample was 105.8 and the standard deviation was 15. Using the sample standard deviation above to estimate the population standard deviation, what is the minimum sample size needed for a 99.5% confidence interval to have a margin of error of no more than 2.3?