Exam 14: Comparing Two Means

Consider the following to answer the question(s) below: A consumer group was interested in comparing the operating time of cordless toothbrushes manufactured by two different companies. They took a random sample of 18 toothbrushes from Company A and 15 from Company B. Each was charged overnight and the number of hours of use before needing to be recharged was recorded. Company A toothbrushes operated for an average of 119.7 hours with a standard deviation of 1.74 hours; Company B toothbrushes operated for an average of 120.6 hours with a standard deviation of 1.72 hours. Do these samples indicate that Company B toothbrushes operate more hours on average than Company A toothbrushes? -Write the null and alternative hypotheses. Assume Company A is group 1 and Company B is group 2.

Consider the following to answer the question(s) below: Data were collected on annual personal time (in hours) taken by a random sample of 16 women and 7 men employed by a medium sized company. The women took an average of 24.75 hours of personal time per year with a standard deviation of 2.84 hours. The men took an average of 21.86 hours with a standard deviation of 3.29 hours. The Human Resources Department believes that women tend to take more personal time than men because they tend to be the primary child care givers in the family. -What is the associated P-value?

Consider the following to answer the question(s) below: Data were collected on annual personal time (in hours) taken by a random sample of 16 women and 7 men employed by a medium sized company. The women took an average of 24.75 hours of personal time per year with a standard deviation of 2.84 hours. The men took an average of 21.86 hours with a standard deviation of 3.29 hours. The Human Resources Department believes that women tend to take more personal time than men because they tend to be the primary child care givers in the family. -At α = 0.05,

Consider the following to answer the question(s) below: Data were collected on annual personal time (in hours) taken by a random sample of 16 women and 7 men employed by a medium sized company. The women took an average of 24.75 hours of personal time per year with a standard deviation of 2.84 hours. The men took an average of 21.86 hours with a standard deviation of 3.29 hours. The Human Resources Department believes that women tend to take more personal time than men because they tend to be the primary child care givers in the family. -What is the value of the test statistic?

Consider the following to answer the question(s) below: A company in the golfing industry is interested in testing its new driver to see if it has greater length off the tee than the best-selling driver. To do this, it has selected a group of golfers of differing abilities and ages. Its plan is to have each player use each of the two clubs to hit five balls. It will record the average length in yards of the drives with each club for each player. -At α = 0.05,

Consider the following to answer the question(s) below: A consumer group was interested in comparing the operating time of cordless toothbrushes manufactured by two different companies. They took a random sample of 18 toothbrushes from Company A and 15 from Company B. Each was charged overnight and the number of hours of use before needing to be recharged was recorded. Company A toothbrushes operated for an average of 119.7 hours with a standard deviation of 1.74 hours; Company B toothbrushes operated for an average of 120.6 hours with a standard deviation of 1.72 hours. Do these samples indicate that Company B toothbrushes operate more hours on average than Company A toothbrushes? -Which of the following statements is true?

Consider the following to answer the question(s) below: Data were collected on annual personal time (in hours) taken by a random sample of 16 women and 7 men employed by a medium sized company. The women took an average of 24.75 hours of personal time per year with a standard deviation of 2.84 hours. The men took an average of 21.86 hours with a standard deviation of 3.29 hours. The Human Resources Department believes that women tend to take more personal time than men because they tend to be the primary child care givers in the family. -The correct null and alternative hypotheses (assuming women are group 1 and men are group 2) are

Consider the following to answer the question(s) below: A consumer group was interested in comparing the operating time of cordless toothbrushes manufactured by two different companies. They took a random sample of 18 toothbrushes from Company A and 15 from Company B. Each was charged overnight and the number of hours of use before needing to be recharged was recorded. Company A toothbrushes operated for an average of 119.7 hours with a standard deviation of 1.74 hours; Company B toothbrushes operated for an average of 120.6 hours with a standard deviation of 1.72 hours. Do these samples indicate that Company B toothbrushes operate more hours on average than Company A toothbrushes? -What is the associated P-value?

Consider the following to answer the question(s) below. A recent study of two brands of golf balls was undertaken to determine whether there is a difference in the mean distance that the two golf ball brands will fly off the tee. To conduct the test, a robot which swings the club at the same speed and with the same swing pattern each time was used. The following data reflect sample data for a random sample of balls of each brand. We assume that the variances of the two groups are the same. Brand A: 234 236 230 227 234 233 228 229 230 238 Brand B: 240 236 241 236 239 243 230 239 243 240 -Which test would be most appropriate for testing this hypothesis?

Consider the following to answer the question(s) below. A recent study of two brands of golf balls was undertaken to determine whether there is a difference in the mean distance that the two golf ball brands will fly off the tee. To conduct the test, a robot which swings the club at the same speed and with the same swing pattern each time was used. The following data reflect sample data for a random sample of balls of each brand. We assume that the variances of the two groups are the same. Brand A: 234 236 230 227 234 233 228 229 230 238 Brand B: 240 236 241 236 239 243 230 239 243 240 -The correct null and alternative hypotheses (assuming Brand A is group 1 and Brand B is group 2) are

Consider the following to answer the question(s) below: A consumer group was interested in comparing the operating time of cordless toothbrushes manufactured by two different companies. They took a random sample of 18 toothbrushes from Company A and 15 from Company B. Each was charged overnight and the number of hours of use before needing to be recharged was recorded. Company A toothbrushes operated for an average of 119.7 hours with a standard deviation of 1.74 hours; Company B toothbrushes operated for an average of 120.6 hours with a standard deviation of 1.72 hours. Do these samples indicate that Company B toothbrushes operate more hours on average than Company A toothbrushes? -What is the value of the test statistic?

Consider the following to answer the question(s) below: A consumer group was interested in comparing the operating time of cordless toothbrushes manufactured by two different companies. They took a random sample of 18 toothbrushes from Company A and 15 from Company B. Each was charged overnight and the number of hours of use before needing to be recharged was recorded. Company A toothbrushes operated for an average of 119.7 hours with a standard deviation of 1.74 hours; Company B toothbrushes operated for an average of 120.6 hours with a standard deviation of 1.72 hours. Do these samples indicate that Company B toothbrushes operate more hours on average than Company A toothbrushes? -The correct value of the test statistic is

Consider the following to answer the question(s) below: A company in the golfing industry is interested in testing its new driver to see if it has greater length off the tee than the best-selling driver. To do this, it has selected a group of golfers of differing abilities and ages. Its plan is to have each player use each of the two clubs to hit five balls. It will record the average length in yards of the drives with each club for each player. -Based on the data, the 90% confidence interval for the difference in the length off the tee is

Consider the following to answer the question(s) below. A recent study of two brands of golf balls was undertaken to determine whether there is a difference in the mean distance that the two golf ball brands will fly off the tee. To conduct the test, a robot which swings the club at the same speed and with the same swing pattern each time was used. The following data reflect sample data for a random sample of balls of each brand. We assume that the variances of the two groups are the same. Brand A: 234 236 230 227 234 233 228 229 230 238 Brand B: 240 236 241 236 239 243 230 239 243 240 -The correct critical value(s) at α = 0.05 (assuming Brand A is group 1 and Brand B is group 2) is(are)

Consider the following to answer the question(s) below. A recent study of two brands of golf balls was undertaken to determine whether there is a difference in the mean distance that the two golf ball brands will fly off the tee. To conduct the test, a robot which swings the club at the same speed and with the same swing pattern each time was used. The following data reflect sample data for a random sample of balls of each brand. We assume that the variances of the two groups are the same. Brand A: 234 236 230 227 234 233 228 229 230 238 Brand B: 240 236 241 236 239 243 230 239 243 240 -At α = 0.05,

Consider the following to answer the question(s) below. A recent study of two brands of golf balls was undertaken to determine whether there is a difference in the mean distance that the two golf ball brands will fly off the tee. To conduct the test, a robot which swings the club at the same speed and with the same swing pattern each time was used. The following data reflect sample data for a random sample of balls of each brand. We assume that the variances of the two groups are the same. Brand A: 234 236 230 227 234 233 228 229 230 238 Brand B: 240 236 241 236 239 243 230 239 243 240 -The correct value of the test statistic (assuming Brand A is group 1 and Brand B is group 2) is

Consider the following to answer the question(s) below: Data were collected on annual personal time (in hours) taken by a random sample of 16 women and 7 men employed by a medium sized company. The women took an average of 24.75 hours of personal time per year with a standard deviation of 2.84 hours. The men took an average of 21.86 hours with a standard deviation of 3.29 hours. The Human Resources Department believes that women tend to take more personal time than men because they tend to be the primary child care givers in the family. -The correct value of the test statistic is

Consider the following to answer the question(s) below: A consumer group was interested in comparing the operating time of cordless toothbrushes manufactured by two different companies. They took a random sample of 18 toothbrushes from Company A and 15 from Company B. Each was charged overnight and the number of hours of use before needing to be recharged was recorded. Company A toothbrushes operated for an average of 119.7 hours with a standard deviation of 1.74 hours; Company B toothbrushes operated for an average of 120.6 hours with a standard deviation of 1.72 hours. Do these samples indicate that Company B toothbrushes operate more hours on average than Company A toothbrushes? -Create and interpret a 90% confidence interval.

Consider the following to answer the question(s) below: Data were collected on annual personal time (in hours) taken by a random sample of 16 women and 7 men employed by a medium sized company. The women took an average of 24.75 hours of personal time per year with a standard deviation of 2.84 hours. The men took an average of 21.86 hours with a standard deviation of 3.29 hours. The Human Resources Department believes that women tend to take more personal time than men because they tend to be the primary child care givers in the family. -The t-test for two means is appropriate in this situation because

Consider the following to answer the question(s) below: A company in the golfing industry is interested in testing its new driver to see if it has greater length off the tee than the best-selling driver. To do this, it has selected a group of golfers of differing abilities and ages. Its plan is to have each player use each of the two clubs to hit five balls. It will record the average length in yards of the drives with each club for each player. -The correct null and alternative hypotheses (assuming the new club is group 1, leading club is group 2, and d = group 1 value - group 2 value) are