Chapter 10, Problem 10.26AC

"Durable press" cotton fabrics are treated to improve their recovery from wrinkles after washing. "Wrinkle recovery angle" measures how well a fabric recovers from wrinkles. Higher is better. Here are data on the wrinkle recovery angle (in degrees) for two types of treated fabrics: Permafresh 12 13 15 11 10 16 14 Hylite 14 19 20 16 A manufacturer wants to know how large is the difference in mean wrinkle recovery angle. Give a 98% confidence interval for the difference in mean wrinkle recovery angle: [three decimal accuracy] [three decimal accuracy]

The Environmental Protection Agency (EPA) has determined that safe drinking water should contain at most 1.3 mg/liter of copper, on average. A water supply company is testing water from a new source and collects water in small bottles at each of 30 randomly selected locations. The company performs a test at the a = 0.05 level of Ho μ = 1.3 : H₂ μ> 1.3 where is the true mean copper content of the water from the new source. Which of the following is true regarding Type I and Type II errors in this setting? A Type I error would be finding convincing evidence that the mean copper content of the water from the new source is greater than 1.3 mg/liter when it really is. A Type II error would be not finding convincing evidence that the true mean copper content of the water from the new source is greater than 1.3 mg/liter when it really is. A Type II error would be not finding convincing evidence that the true mean copper content of the water from the new source is greater than 1.3 mg/liter…

The "spring-like effect" in a golf club could be determined by measuring the coefficient of restitution (the ratio of the outbound velocity to the inbound velocity of a golf ball fired at the clubhead). Twelve randomly selected drivers produced by two clubmakers are tested and the coefficient of restitution measured. The data follow: Club 1: 0.8406, 0.8104, 0.8234, 0.8198, 0.8235, 0.8562, 0.8123, 0.7976, 0.8184, 0.8265, 0.7773, 0.7871  Club 2: 0.8305, 0.7905, 0.8352, 0.8380, 0.8145, 0.8465, 0.8244, 0.8014, 0.8309, 0.8405, 0.8256, 0.8476 Test the hypothesis that both brands of ball have equal mean overall distance. Use α = 0.05 and assume equal variances. Question: Reject H0 if t0 < ___ or if t0 > ___.

The degenerative disease osteoarthritis most frequently affects weight-bearing joints such as the knee. Stance duration was measured in seperate samples of younger and older adults. Test the claim that the true average stance is different between younger and older adults  Younger: n = 22, xbar = 801, s =117 Older: n = 16, xbar = 780, s = 81 Let population 1 = younger population 2 = older what is the appropriate procedure to test the claim? what is the degrees of freedom? Use the conservative formula At 0.05 significance level, what is/are the critical value/s? what is the value statistic?  what is the margin of error? does the result of the confidence interval estimate aggrees with the hypothesis test

"Durable press" cotton fabrics are treated to improve their recovery from wrinkles after washing. "Wrinkle recovery angle" measures how well a fabric recovers from wrinkles. Higher is better. Here are data on the wrinkle recovery angle (in degrees) for two types of treated fabrics: Permafresh Hylite 16 16 14 19 10 20 11 14 13 18 12 15 15   A manufacturer wants to know how large is the difference in mean wrinkle recovery angle.Give a 95% confidence interval for the difference in mean wrinkle recovery angle: (  ,  ) [three decimal accuracy] [three decimal accuracy]

Suppose that a customer is purchasing a car. He conducts an experiment in which he puts 10 gallons of gas in the car and drives it until it runs out of gas. He conducts this experiment 15 Sample mean for Car 2 x= 245 mi / 10 gal (Type an integer or decimal rounded to one decimal place as needed.) times on each car and records the number of miles driven. Full data set Car 1 Median for Car 1 M= mi / 10 gal (Type an integer or decimal rounded to one decimal place as needed.) 245 242 215 244 220 265 291 160 284 251 169 319 257 306 267 Car 2 Median for Car 2 230 242 M=O mi / 10 gal 206 214 236 256 245 255 241 264 (Type an integer or decimal rounded to one decimal place as needed.) 276 252 250 251 257

"Durable press" cotton fabrics are treated to improve their recovery from wrinkles after washing. "Wrinkle recovery angle" measures how well a fabric recovers from wrinkles. Higher is better. Here are data on the wrinkle recovery angle (in degrees) for two types of treated fabrics: Permafresh Hylite 15 17 12 14 13 16 16 15 14 18 A manufacturer wants to know how large is the difference in mean wrinkle recovery angle. Give a 98% con fidence interval for the difference in mean wrinkle recovery angle: [three decimal accuracy] [three decimal accuracy]

Dr. Johnson is interested in the difference in mean systolic blood pressure between groups. He performs analysis and finds a mean difference of 0.0005 mmHg in systolic blood pressure with a p value of 0.001. Dr. Johnson's findings are: a) statistically insignificant and practically significant  b) statistically significant and practically significant  c) statistically insignificant and practically insignificant  d) statistically significant but practically ins

Compute a 95% CI for the mean age.