Researchers from a certain country were interested in how characteristics of the spleen of residents in their tropical environment compare to those found elsewhere in the world. The researchers randomly sampled 93 males and 107 females in their country. The mean and standard deviation of the spleen lengths for the males were 11.2 cm and 0.8 cm, respectively, and those for the females were 10.1 cm and 0.7 cm, respectively. Determine a 95% confidence interval for the difference between mean spleen lengths of males and females in this country. Click here to view page 1 of the table of critical values of t. Click here to view page 2 of the table of critical values of t. Let population 1 be all males in the country and let population 2 be all females in the country. The 95% confidence interval for H₁-H₂ is (Round to three decimal places as needed. Use ascending order.)

Given that the researcher wants to be sure the mean difference in the change in hemoglobin levels has a margin of error no more than 0.2 g/dL and the difference in the stand deviation between the mean hemoglobin levels for the two forms of iron supplements used to treat anemia is 1.2 g/dL, what is the desired number of recruits for the study, assuming the individuals will participate in a crossover trial, if the study’s attrition rate is expected to be .25? Group of answer choices n = 139 n = 554 n = 185 n = 55,320

Researchers from a certain country were interested in how characteristics of the spleen of residents in their tropical environment compare to those found elsewhere in the world. The researchers randomly sampled 93 males and 107 females in their country. The mean and standard deviation of the spleen lengths for the males were 10.8 cm and 0.9 cm, respectively, and those for the females were 10.2 cm and 0.7 cm, respectively. At the 5% significance level, do the data provide sufficient evidence to conclude that a difference exists in the mean spleen lengths of males and females in the country? Click here to view page 1 of the table of critical values of t. Click here to view page 2 of the table of critical values of t. O E. Ho: H1 H₂ Hai Hg = H2 Compute the test statistic. =(Round to two decimal places as needed.) Determine the critical value(s). t= OF. Ho: H1 H₂ Ha: H1 H₂ 0 (Round to three decimal places as needed. Use a comma to separate answers as needed.) What is the conclusion of the…

In an old study, the weight of a certain breed of pig had a standard deviation of 3.8 pounds. What sample size should be used to estimate the mean weight of that breed of pig for a new study? Assume a margin of error of 0.7 pounds and a confidence level of 99% is desired.

In a recent year, a sample of the South American Redeye Piranha was collected by fishermen on a particular river. Wildlife biologists regard this sample as a random sample of all Redeye Piranha in that river. The mean length of the 60 fish in the sample was 12.88 cm, and a 99% confidence level for the true mean length of all Redeye Piranha in that river is 12.09 cm to 13.67 cm.  Explain what would happen to the length of the interval if the confidence level were decreased to 95%.

Looking at the number of chocolate chips in a sample of 40 Chips Ahoy regular cookies, we get a mean of 23.95 chocolate chips and a standard deviation of 2.55 chocolate chips. Construct a 99% confidence interval estimate of the mean number of chocolate chips in all such cookies.

A study has been made to compare the nicotine contents of two brands of cigarettes. Ten cigarettes of Brand A had an average nicotine content of 4.3 milligrams with a standard deviation of 0.6 milligram. Eight cigarettes of Brand B had an average nicotine content of 3 milligrams with a standard deviation of 0.4 milligram. Assume that the two sets of data are independent random samples from normal populations with equal variances. Answer the following, and round off your answer to three decimal places. (a) Find a pooled estimate of the population standard deviation. (b) Construct a 95% confidence interval for the difference between the mean nicotine contents of the two brands of cigarettes. (☐☐)

Bone mineral density (BMD) is a measure of bone strength. Studies show that BMD declines after age 45. The impact of exercise may increase BMD. A random sample of 59 women between the ages of 41 and 45 with no major health problems were studied. The women were classified into one of two groups based upon their level of exercise activity: walking women and sedentary women. The 39 women who walked regularly had a mean BMD of 5.96 with a standard deviation of 1.22. The 20 women who are sedentary had a mean BMD of 4.41 with a standard deviation of 1.02. Which of the following inference procedures could be used to estimate the difference in the mean BMD for these two types of women

The growing seasons for a random sample of 35 U.S. cities were recorded, yielding a sample mean of 190.7 days and the population standard deviation of 54.2 days. Find a 95% confidence interval estimate of the true mean for the growing season in all U.S. cities.

in a test of the effectiveness of garlic for lowering cholesterol, 43 subjects were treated with garlic in a processed tablet form. Cholesterol levels were measured before and after the treatment. The changes in their levels of LDL cholesterol have a mean of 5.7 and a standard deviation of 17.7. Construct a 99% confidence interval estimate of the mean net change in LDL cholesterol after the garlic treatment. What does the confidence interval suggest about the effectiveness of garlic and reducing LDL cholesterol?