Answers:2. t = 0.656, do not reject Ho: there is no evidence that this year's students are performing differently than students in previous years.3. chi-square = 7.997, Do not reject H0; no evidence that the variance is significantly less than 175. chi-square = 11.250, Do not reject H0; no evidence that the variance is significantly greater than 175.4. 3.973 to 13.5219 2. In the past, students in a particular course have achieved a mean Xmas exam score of 72.6, with a standard deviationof 12.5. This year, 15 students in one section achieved a mean Xmas exam score of 72.2, while 10 students inanother section achieved a mean Xmas exam score of 77.3. Is the overall (grand) mean of the 25 students in thisyear's two sections significantly different from the mean obtained in previous years (a ≤.05)?3. A new pollution control device for automobiles is claimed not only to reduce carbon monoxide emission but also toincrease a car's miles per gallon. To test the latter claim, the mileage per gallon of 10 randomly selected cars ismeasured first without and then with the device, yielding the following data:Miles per gallonCar Without Device12345678910282044720111134948With Device3236102093214211446Typically, the variance of the mileage per gallon of cars not fitted with the device is 175. Is the variance of the 10cars in this study significantly less than this when they were driven with the device (a ≤.05)? Is their variancesignificantly greater than 175 when they were driven without the device? (a ≤.05)?4. The lower value of a 90% confidence interval for the variance in maze-running times of a sample of 31 rats is 4.62.Based on this, form a 98% confidence interval for ².Answers:1.a) t = 3.033, reject Ho: there is evidence for a significant increase in the number of errors1b) 377.35 to 423.992. t = .656, do not reject Ho: there is no evidence that this year's students are performing differently than students inprevious years.3. chi-square = 7.997, Do not reject Ho; no evidence that the variance is significantly less than 175. chi-square11.250, Do not reject Ho; no evidence that the variance is significantly greater than 175.4. 3.973 to 13.5219=

Question

Answers:2. t = 0.656, do not reject Ho: there is no evidence that this year's students are performing differently than students in previous years.3.  chi-square = 7.997, Do not reject H0; no evidence that the variance is significantly less than 175.  chi-square   = 11.250, Do not reject H0; no evidence that the variance is significantly greater than 175.4. 3.973 to 13.5219 2. In the past, students in a particular course have achieved a mean Xmas exam score of 72.6, with a standard deviationof 12.5. This year, 15 students in one section achieved a mean Xmas exam score of 72.2, while 10 students inanother section achieved a mean Xmas exam score of 77.3. Is the overall (grand) mean of the 25 students in thisyear's two sections significantly different from the mean obtained in previous years (a ≤.05)?3. A new pollution control device for automobiles is claimed not only to reduce carbon monoxide emission but also toincrease a car's miles per gallon. To test the latter claim, the mileage per gallon of 10 randomly selected cars ismeasured first without and then with the device, yielding the following data:Miles per gallonCar Without Device12345678910282044720111134948With Device3236102093214211446Typically, the variance of the mileage per gallon of cars not fitted with the device is 175. Is the variance of the 10cars in this study significantly less than this when they were driven with the device (a ≤.05)? Is their variancesignificantly greater than 175 when they were driven without the device? (a ≤.05)?4. The lower value of a 90% confidence interval for the variance in maze-running times of a sample of 31 rats is 4.62.Based on this, form a 98% confidence interval for ².Answers:1.a) t = 3.033, reject Ho: there is evidence for a significant increase in the number of errors1b) 377.35 to 423.992. t = .656, do not reject Ho: there is no evidence that this year's students are performing differently than students inprevious years.3. chi-square = 7.997, Do not reject Ho; no evidence that the variance is significantly less than 175. chi-square11.250, Do not reject Ho; no evidence that the variance is significantly greater than 175.4. 3.973 to 13.5219=

Accepted Answer

The sample size, The mean Xmas exam score, The sample standard deviation, The sample size in the…