Statistics homework 9.2

6. In a survey. 1400 adults in a certain country were asked how many hours they worked in the previous week. Based on the results. a 95% condence interv mean number of hours worked was lower bound: 41.9 and upper bound: 44.5. Which of the following represents a reasonable interpretation of the result? that are not reasonable. explain the aw. Complete pans (a) through (d) below. Piiiit (a) There is a 95% chance the mean number of hours worked by adults in this country in the previous week was between 41.9 hours and 44.5 hours. 0 A. Flawed. This interpretation implies that the mean is only for last week. 0 5. Correct. This interpretation is reasonable. 0 C. Flawed. This interpretation makes an implication about individuals rather than the mean. 0 D. Flawed. This interpretation implies that the population mean varies rather than the interval. (b) We are 95% condent that the mean number of hours worked by adults in this country in the previous week was between 41.9 hours and 44.5 hours. 0 A. Flawed. This interpretation makes an implication about individuals rather than the mean. O B. Flawed. This interpretation does not make it clear that the 95% is the probability that the mean is within the interval. 0 C. Flawed. This interpretation implies that the population mean varies rather than the interval. 0 D. Correct. This interpretation is reasonable. (c) 95% of adults in this country worked between 41.9 hours and 44.5 hours last week. O A. Flawed. This interpretation makes an implication about individuals rather than the mean. 0 B. Flawed. This interpretation implies that the mean is only tor last week. 0 C. Flawed. This interpretation does not make it clear that the 95% is the probability that the mean is within the interval. 0 D. Correct. This interpretation is reasonable. (d) We are 95% condent that the mean number of hours worked by adults in a particular area of this country in the previous week was between 41.9 hours and 44.5 hours. 0 A. Flawed. The interpretation should be about the mean number of hours worked by adults in the whole country. not about adults in the particular area. 0 B. Correct. This interpretation is reasonable. 0 C. Flawed. This interpretation implies that the population mean varies rather than the interval. 0 D. Flawed. This interpretation makes an implication about individuals rather than the mean. 7. The trade magazine QSR routinely checks the drive-through service times of fast-food restaurants. A 95% condence interval that results from examining 641 customers in Taco Bell's drive-through has a lower bound of 167.0 seconds and an upper bound of 172.2 seconds. Complete parts (a) through (c). (a) What is the mean service time from the 641 customers? The mean service time from the 641 customers is seconds (Type an integer or a decimal. Do not round.) (b) What is the margin of error for the condence interval? The margin of error is seconds. (Type an integer or a decimal. Do not round.) (c) Interpret the confidence interval. Select the correct choice below and ll in the answer boxes to complete your choice. (Type integers or decimals. Do not round.) 0 A- One can be i:% condent that the mean drivethrough service time of Taco Bell is I: seconds. 0 B- The mean drive-through service time of Taco Bell is I: seconds I:% of the time. O C- There is a % probability that the mean drive-through service time of Taco Bell is between seconds and seconds. 0 D. One can be i:|% condent that the mean drive-through service time 01 Taco Bell is between |:| seconds and |: seconds. 8. In a survey conducted by the Gallup Organization. 1100 adult Americans were asked how many hours they worked in the previous week. Based on the results. a 95% confidence interval for the mean number of hours worked had a lower bound of 42.7 and an upper bound of 44.5. Provide two recommendations for decreasing the margin of error of the interval. Select the two recommendations that would decrease the margin of error of the interval. U A. Decrease the sample size. El B. Increase the confidence level. D C. Decrease the condence level. El D. anrease the sample size. [I E. Use fewer degrees of freedom. I] F. Decrease the standard deviation of hours worked. 9- A survey was conducted that asked 1011 people how many books they had read in the past year. Results indicated that )1 = 11.8 books and 5 =16.6 books. Constmct a 90% condence interval for the mean number of books people read. Interpret the interval. 4 Click the icon to view the table of critical tvalues. Constmct a 90% condence interval for the mean number of books people read and interpret the result. Select the correct choice below and ll in the answer boxes to complete your choice. (Use ascending order. Round to two decimal places as needed.) 0 A- it repeated samples are taken. 90% of them will have a sample mean between :I and :l. O 3- There is 90% condence that the population mean number of books read is between and I O C- There is a 90% probability that the true mean number of books read is between I and 4: Table of Critical tValues riahtui r-Dktrlmtiun Are-hm" Ti Deant Freedom 0.25 0.21] 0.15 0.10 0.05 0.025 am 0.01 0.005 011025 0.0" 0.0015 1 1.009 1.176 1.963 3.1778 6.314 12.706 15.194 31.821 63.651 1.27121 11 1309 696.519 1 0.816 1.06! 1.396 LS\" 2.92!) 4.303 4.949 6965 997.5 14.0w 12327 11.591 3 0.7\" 0.97! mu 1538 US 3.182 1487. 4.541 5341 745] 10115 121'\" 4 0.141 0.941 1.1913 1.111 2.112 2.776 7.999 1.147 4.604 5598 7171 8.610 5 0.727 0.921) 1.156 1.476 2.015 2.371 2.757 1.365 4.1132. 4.771 5.891 6.869 6 0.118 0.1116 1.134 1.440 1.94] 2.447 2.612 1.141 1.707 4311 5.218 5.939 7 9.711 0.896 1.119 1.415 1195 2.365 1517 2.998 3.4m 4.93 4.115 5.498 3 0.715 0.889 1.118 1.197 1.960 2306 7.449 2896 3.155 3.81! 4.561 51141