A study shows that running increases the percent resting metabolic rate (RMR) in older women. The average RMR of 25 elderly women runners was 33.1% higher than the average RMR of 25 sedentary elderly women, and the standard deviations were reported to be 10.5% and 10 2%, respectively. Was there a significance increase in RMR of the women runners over the sedentary women? Assume the populations to be approximately normally distributed with equal variances. Use a P-value in the conclusion Click here to view page 1 of the table of critical values of the t-distribution. Click here to view page 2 of the table of critical values of the t-distribution. Let sample 1 be the women runners and let sample 2 be the sedentary women. State the null and alternative hypotheses Hg. Họ th H₁ H₁ H₂

Pilots who cannot maintain regular sleep hours due to their work schedule often suffer from insomnia. A recent study on sleeping patterns of pilots focused on quantifying deviations from regular sleep hours. A random sample of 28 commercial airline pilots was interviewed, and the pilots in the sample reported the time at which they went to sleep on their most recent working day. The study gave the sample mean and standard deviation of the times reported by pilots, with these times measured in hours after midnight. (Thus, if the pilot reported going to sleep at p.m., the measurement was -1.) The sample mean was 0.8 hours, and the standard deviation was 1.6 hours. Assume that the sample is drawn from a normally distributed population. Find a 90% confidence interval for the population standard deviation, that is, the standard deviation of the time (hours after midnight) at which pilots go to sleep on their work days. Then give its lower limit and upper limit.

A drug which is used for treating diabetes has potentially dangerous side effects if it is taken in doses which are larger than the required dosage for the treatment. A medical researcher believes that the variance in dosage is different for two tablets made by different production facilities. The sample variance of a sample of 11 dosages of tablet "A" is 0.013 . The sample variance of a sample of 28 dosages of tablet "B" is 0.01 . Construct the 90% confidence interval for the ratio of the population variances. Round your answers to four decimal places.

The distribution of the student heights at a large college is approximately bell shaped. If the mean height is 66 inches,and approximately 95% of the heights fall between 32 and 100 inches, then, the standard deviation of the heightdistribution is approximately equal to

Give a 99.8% confidence interval, for μ₁ −μ₂ given the following information. n₁ = 35, x₁ = 1 2.41, s₁ = 0.39 81 n₂ = 20, x₂ = 2.62, s₂ = 0.83 2 -0.21 ✓0.69 X Use Technology Rounded to 2 decimal places.

Ritalin has been shown to increase attention span and improve academic performance in children with ADHD (Evans et al., 2001). To demonstrate the effectiveness of the drug, a researcher selects a sample of n = 20 children diagnosed with ADHD and measures each child’s attention span before and after taking the drug. The data show an average increase of attention span of MD = 4.8 minutes with a variance of s2 = 125 for the sample of difference scores.    Is this result sufficient to conclude that Ritalin significantly improves attention span? Use a one-tailed test at .05.    Compute the 80% confidence interval for the mean chance in attention span for the population.

A researcher decides to measure anxiety in group of bullies and a group of bystanders using a 23-item, 3 point anxiety scale.  Assume scores on the anxiety scales are normally distributed and the variance among the group of bullies and bystanders are the same. A group of 30 bullies scores an average of 21.5 with a sample standard deviation of 10 on the anxiety scale.  A group of 27 bystanders scored an average of 25.8 with a sample standard deviation of 8 on the anxiety scale. You do not have any presupposed assumptions whether bullies or bystanders will be more anxious so you formulate the null and alternative hypothesis based on that.

A basketball coach believes that the variance of the heights of adult male basketball players is different from the variance of heights for the general population of men. The sample variance of heights, measured in inches, for a random sample of 19 basketball players is 14.22. The sample variance for a random sample of 18 other men is 34.49. Assume that both population distributions are approximately normal and test the coach’s claim using a 0.10 level of significance. Does the evidence support the coach’s claim? Let male basketball players be Population 1 and men in general be Population 2.   Step 1 of 3:  State the null and alternative hypotheses for the test. Fill in the blank below. H0: σ21=σ22: Ha: σ21⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯σ22 Step 2 of 3:  Compute the value of the test statistic. Round your answer to four decimal places. Step 3 of 3:  Draw a conclusion and interpret the decision.

The salaries of professional baseball players are heavily skewed right with a mean of $3.2 million and a standard deviation of $2 million. The salaries of professional football players are also heavily skewed right with a mean of $1.9 million and a standard deviation of $1.5 million. A random sample of 40 baseball players’ salaries and 35 football players’ salaries is selected. The mean salary is determined for both samples. Let  represent the difference in the mean salaries for baseball and football players. Which of the following represents the shape of the sampling distribution for ? skewed right since the populations are both right skewed skewed right since the differences in salaries cannot be negative approximately Normal since both sample sizes are greater than 30 approximately Normal since the sum of the sample sizes is greater than 30