The article “Hatching Distribution of Eggs Varying in Weight and Breeder Age” (S. Viera, J. Almeida, et al., Brazilian Journal of Poultry Science, 2005: 73–78) presents the results of a study in which the weights of 296 eggs from 27-week-old breeding hens averaged 54.1 g with a standard deviation of 4.4 g, and weights of 296 eggs from 59-week-old hens averaged 72.7 g with a standard deviation of 4.7 g. Find a 95% confidence interval for the difference between the mean weights.

A purchasing manager for a large university is investigating which brand of LCD projector to purchase to equip their classrooms. Of major concern is the longevity of the light bulbs used in the projectors. The purchasing manager has narrowed down the choice of projector to two brands, Infocus and Proxima, and wishes to determine if there is any difference between the two brands in the mean lifetime of the bulbs used. The purchasing manager obtained eight projectors of each brand for testing over the last several academic terms. The number of hours the bulbs lasted on each of the eight projectors is given in the table. Lifetimes of light bulbs (hours) Infocus 745, 955, 1085, 756, 901, 839, 858, 931 Proxima 1012, 988, 957, 920, 878, 1130, 657, 743 Send data to calculator Assume that the two populations of lifetimes are normally distributed and that the population variances are equal. Can we conclude, at the 0.01 level of significance, that u, the mean lifetime of light bulbs in Infocus…

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 high-profile consulting company chooses its new entry-level employees from a pool of recent college graduates using a five-step interview process. Unfortunately, there are usually more candidates who complete the interview process than the number of new positions that are available. As a result, cumulative GPA is used as a tie-breaker. GPAs for the successful interviewees are Normally distributed, with a mean of 3.3 and a standard deviation of 0.4 . What proportion of candidates have a GPA under 3.0 ?   0.227   0.023   0.551   0.773

Is there any difference in the variability in golf scores for players on the LPGA Tour (the women's professional golf tour) and players on the PGA Tour (the men's professional golf tour)? A sample of 20 tournament scores from LPGA events showed a standard deviation of 2.4623 strokes, and a sample of 30 tournament scores from PGA events showed a standard deviation of 2.2118. Conduct a hypothesis test for equal population variances to determine whether there is any statistically significant difference in the variability of golf scores for male and female professional golfers. Use a = = 0.10. Ho : o Ha : o - Select your answer - - Select your answer What is your conclusion? There is - Select your answer V significant difference in the variances. - Select your answer -

Suppose that you want to compare the means of several treatments in a randomized block ANOVA. If given the choice between using the randomized block ANOVA test and the Friedman test, which one would you choose if outliers occur in the sample data? Explain your answer.

The article “Well-Fed Crickets Bowl Maidens Over” (Nature Science Update, February 11, 1999) reported that female field crickets are attracted to males with high chirp rates and hypothesized that chirp rate is related to nutritional status. The usual chirp rate for male field crickets was reported to vary around a mean of 60 chirps per second. To investigate whether the chirp rate was related to nutritional status, investigators fed 22 male crickets a high protein diet for 8 days, after which chirp rate was measured. Let:  The parameter μμ be the mean chirp rateof male crickets on a high protein diet for 8 days.    Given: The mean chirp rate for the random sample of crickets on the high protein diet was reported to be 65.32 chirps per second with a standard deviation of 12. Research Question: Is there convincing evidence that the mean chirp rate for crickets on a high protein diet implies an advantage in attracting the ladies? It is known that the researchers did not want to…

A research article reported that for a random sample of 850 meal purchases made at fast food chain A, the mean number of calories was 1,004, and the standard deviation was 489. For a random sample of 2,108 meal purchases made at fast food chain B, the mean number of calories was 905, and the standard deviation was 622. Based on these samples, is there convincing evidence that the mean number of calories in fast food chain B meal purchases is less than the mean number of calories in fast food chain A meal purchases? (Test the relevant hypotheses using a 0.05 level of significance. Use ?1 for fast food chain B and ?2 for fast food chain A.)   State the appropriate null and alternative hypotheses.   Find the test statistic and P-value. (Use SALT. Round your test statistic to one decimal place and your P-value to three decimal places.) t= P-value=   State the conclusion in the problem context. We fail to reject H0. There is convincing evidence that the mean number of calories in fast food…