The values associated with a two-sided 90% of the Student’s t distribution and 21 degrees of freedom are    A. ± 1.721  B. ± 1.96  C. ± 1.319  D. ± 2.96

Total plasma volume is important in determining the required plasma component in blood replacement therapy for a person undergoing surgery. Plasma volume is influenced by the overall health and physical activity of an individual. Suppose that a random sample of 40 male firefighters are tested and that they have a plasma volume sample mean of x = 37.5 ml/kg (milliliters plasma per kilogram body weight). Assume that o = 7.10 ml/kg for the distribution of blood plasma. When finding an 99% confidence interval, what is the critical value for confidence level? (Give your answer to two decimal places.) (a) Find a 99% confidence interval for the population mean blood plasma volume in male firefighters. What is the margin of error? (Round your answers to two decimal places.) lower limit upper limit margin of error (b). What conditions are necessary for your calculations? (Select all that apply.) n is large the distribution of volumes is normal o is unknown the distribution of volumes is uniform…

Will your flight get you to your destination on​ time? To the right are a histogram and summary statistics for the percentage of delayed arrivals each month from 2001 thru 2006. Consider these data to be a representative sample of all months. There is no evidence of a time trend.​ (The correlation of Flights Delayed​ % with time is r=0.0160.016​.) n= 72 x= 24.5556 s= 3.34564 ​a) Check the assumptions and conditions for inference about the mean. Select all that apply. A. All of the assumptions and conditions for inference about the mean are met. B. The​ 10% condition is not met. C. The randomization condition is not met and the sample is not suitably representative. D. The independence assumption is not met. E. The nearly normal condition is not met. ​b) Find a​ 99% confidence interval for the true percentage of flights that arrive late. ___ < (Delayed Flight)< ___ ​(Round to two decimal places as​ needed.) ​c) Interpret this interval for a traveler planning to fly. Choose the…

John wants to know whether a common prescribed drug does improve the attention span of students with attention deficit disorder (ADD). He knows that the mean attention span for students with ADD who are not taking the drug is 2.3 minutes long. His sample of 12 students taking the drug yielded a mean of 4.6 minutes. John can find no information regarding σx, so he calculated s² x =1.96 a. Identify the independent and dependent variables. b. In a sentence, state the null hypothesis being tested. c. Using symbols, state the null and alternative hypotheses. d. Determine the critical regions using a one-tailed test with alpha = .05.