\fons 1 of 2 Automatic Zoom 1. Doctors at a technology research facility randomly assigned equal numbers of people to type a manuscript using two different types of computer keyboards, either a standard keyboard, or an ergonomic keyboard. They wanted to see if people could type faster on the ergonomic keyboard. After collecting data for several days, the researchers tested the null hypothesis (Ho) that the mean typing speed was the same on both keyboards, against the alternative hypothesis (Ha) that the mean typing speed is faster on the ergonomic keyboard and found a p-value=0.22. Which is true? The people using ergonomic keyboards type 22% more words per minute. If there is no difference in average typing speeds of the two types of keyboards, we would expect to see a difference in average typing speed at least this great in about 22% of similar experiments. There's a 22% chance that there's really no difference in typing speed. d. There's a 22% chance another experiment will give these same results A relief fund is set up to collect donations for the families affected by a recent storm. People were contacted by either telephone or mail and asked to make contributions. A random sample of 400 people shows that 28% of those 200 who were contacted by telephone made contributions compared to only 18%% of the 200 who received first-class mail requests. Which formula calculates the 95% confidence interval for the ofference in the proportions of people who make donations if contacted by telephone or first-class mail? A) (0.28- 0.18): 1.96,- (0.23 )(0.77) B) (0 28 - 0.18) 1.96, (0.23 )(0.77) (0.23)(0.77) 200 200 200 C) (0.28- 0.18)=1.96, (0.23)(0.77) D) (0.28 - 0.18) +1.96, (0.28)(0.72) (0.18)(0.82) 400 200 200 8. An experiment was conducted in which two groups of teenagers were given manual tasks to complete while listening to music. One group listened to their choice of music and the other group listened to classical music. They were later asked if they enjoyed the tasks. The 95% confidence interval for the difference in the proportion who enjoyed the task with their choice of music and the proportion who enjoyed the task with classical music was (0.02 0.13). Interpret this interval a. I am 95%% confident that the proportion of teenagers who enjoyed the task while listening to their choice of music is between 2% and 13%. b. I am 95% confident that the proportion of teenagers who enjoyed the task is between 2% and 13% higher for the group who listened to classical music compared to listening to their choice of music. c. I am 95% confident that the proportion of teenagers who enjoyed the task is between 2% and 13% higher for the group who listened to their choice of music compared to listening to classical music. d. I am 95% confident that the proportion of teenagers who enjoyed the task while listening to classical music is between 2% and 13%.ions 2 of 2 + Automatic Zoom + 4. You suspect minority students are not as supportive of the new principal of a large school because of a few recent conflicts on campus. You randomly choose students and ask them if they think the principal is doing a good job. You find that 45 out of 56 white students and 21 out of 33 minority students surveyed support the principal. Find the test statistic for the difference in proportions of white students and minority students who support the principal. (All calculations done with 3 decimal figures) 1.75 C. 2.56 b. 2.54 d. 3.72 An insurance company wants to save money repairing cars involved in accidents. They wonder if they will save money by choosing Repair Shop A over Shop B for all their repairs. From a random sample of bills at both repair shops, Repair Shop A had a mean repair cost of $2,186 with a standard deviation of $587 for 17 cars, while Repair Shop B had a mean repair cost of $2,585 with a standard deviation of $777 for 15 cars. How much is the mean difference between the two repair shops with 95%% confidence? (Round to nearest dollar) a. (-$751, -$47) c. (-$103, $901 b. (-$901, $103) d. ( $47, $751) You suspect minority students are not as supportive of the new principal of a large school because of a few recent conflicts on campus. You randomly choose students and ask them if they think the principal is doing a good job and find a p-value of 0.0401 when testing the difference in proportions of white students and minority students who support the principal. What should be your decision and conclusion? Since the p-value is large, I fail to reject Ho. There is not enough evidence to say that the proportion of minority students who support the principal is less the proportion of white students who support the principal. Since the p-value is large, I fail to reject Ho. There is not enough evidence to say that the proportion of white students who support the principal is less the proportion of minority students who support the principal. Since the p-value is small, I reject Ho. There is enough evidence to say that the proportion of white students who support the principal is less the proportion of minority students who support the principal. Since the p-value is small, I reject Ho. There is enough evidence to say that the proportion of minority students who support the principal is less the proportion of white students who support the principal