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.)

The pH of rain, measured at a weather station in Michigan, was observed for 39 consecutive rain storms. The sample mean is 4.6982 and the sample variance is 0.39623. Obtain a 99% confidence interval for the mean pH of the population of storms at that location.

A car manufacturer wants to estimate the average miles-per-gallon highway rating for a new model. From experience with similar models, the manufacturer believes the miles-per-gallon standard deviation is 4.6. A random sample of 100 highway runs of the new model yields a sample mean of 32 miles per gallon. Give a 95% confidence interval for the population average miles-per-gallon highway rating.

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%.

The mean and standard deviation of the quality grade points of a random sample of 36 students from a large population are 2.6 and 0.3 respectively. The 99% confidence interval for the mean of the entire population is

People who diet can expect to lose an average of 2 kg in a month. In a  book, the authors claim that people who follow a new diet will lose an average of more than 2 kg in a month. The weight losses of the 18 people in a random sample who had followed the new diet for a month were noted. The sample mean was 2.1 kg and the standard deviation was 0.5 kg. Test the authors’ claim at the 5% significance level

Obtain the confidence limits for the ratio of variances of two normal populations.