Here are the measurements of engine crankshafts. : 224.120 224.001 224.017 223.982 223.989 223.961 223.960 224.089 223.987 223.976 223.902 223.980 224.098 224.057 223.913 223.999 The data has a σ =.060
In a randomized comparative experiment on the effect of calcium in the diet on blood pressure, researchers divided 54 healthy males at random into 2 groups. 1 group received calcium, the other a placebo. A the beginning of the study, the researchers measured many variables on the subjects. The paper reporting the study gives xbar = 114.9 and s= 9.3 for the seated systolic blood pressure of the 2 members of the placebo group.
a) Calculate and interpret a 99% confidence interval (a t* distribution) for the mean blood pressure in the population from which the subjects were recruited. (10.67)
A nationwide random survey of 1500 adults asked about attitudes toward “alternative medicine” such as acupuncture, massage therapy, and herbal therapy. Among the respondents, 660 said they would use alternative medicine if traditional medicine was not producing the results they wanted.
a) Construct and interpret a 95% confidence interval for the proportion of all adults who would use alternative medicine. (10.69)
Variation is inherent in the production of high resolution video terminals. Careful study has shown that when the process is operating properly, the standard deviation of the tension readings is σ = 43. Here are the tension readings from an SRS of 20 screens from a single day’s production:
269.5 297 269.6 283.3 304.8 280.4 233.5 257.4 317.5
327.4 264.7 307.7 310 343.3 328.1 342.6 338.8 340.1
a) Using the 4 steps necessary for a confidence intervals construct and interpret a 90% confidence inteval for the mean tension of all the screens produced on this day.