CHAPTER EIGHT INTERVAL estimate MULTIPLE selection QUESTIONS In the adhering to multiple an option questions, circle the exactly answer. 1. As soon as s is offered to estimate (, the margin the error is computed by utilizing a. Normal circulation b. T distribution c. The average of the sample d. The median of the population Answer: b 2. As the variety of degrees of flexibility for a t circulation increases, the difference between the t distribution and the traditional normal circulation a. Becomes bigger b. Becomes smaller c. Stays the same d. No one of these alternatives is correct.

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Answer: b 3. Because that the interval estimation of (when (is known and the sample is large, the suitable distribution to usage is a. The normal circulation b. The t distribution with n degrees of flexibility c. The t distribution with n + 1 degrees of freedom d. The t circulation with n + 2 levels of liberty Answer: a 4. An estimate of a population parameter that offers an expression of values believed to contain the value of the parameter is recognized as the a. Confidence level b. Interval estimate c. Parameter worth d. Populace estimate Answer: b 5.

The value included and subtracted from a suggest estimate in stimulate to build an interval estimate of the populace parameter is recognized as the a. Trust level b. Margin the error c. Parameter estimate d. Interval estimate Answer: b 6. If one interval calculation is said to be created at the 90% trust level, the confidence coefficient would certainly be a. 0. 1 b. 0. 95 c. 0. 9 d. 0. 05 Answer: c 7. Anytime the population standard deviation is unknown and also the population has a regular or near-normal distribution, which circulation is provided in occurring an term estimation? a. Standard circulation b. Circulation c. Alpha circulation d. T circulation Answer: d 8. In term estimation, the t distribution is applicable only once a. The population has a typical of less than 30 b. The sample standard deviation is provided to calculation the population standard deviation c. The variance that the populace is well-known d. The traditional deviation that the population is recognized Answer: b 9. In arising an term estimate, if the population standard deviation is unknown a. It is difficult to construct an interval calculation b. The standard deviation is came down on using the variety c. The sample traditional deviation have the right to be used d. T is assumed the the population standard deviation is 1 Answer: c 10. In order to use the normal distribution for interval estimate of (when (is known and also the sample is really small, the population a. Should be very large b. Must have actually a normal circulation c. Have the right to have any kind of distribution d. Must have actually a median of at least 1 Answer: b 11. Indigenous a population that is not typically distributed and whose typical deviation is not known, a sample that 6 items is selected to build an interval estimate for the mean of the populace ((). A. The normal circulation can be used. B. The t distribution with 5 levels of flexibility must it is in used.. The t distribution with 6 levels of freedom must it is in used. D. The sample size have to be increased. Answer: d 12. A sample that 200 elements from a populace is selected, and the typical deviation that the sample is computed. Because that an interval estimate of (, the ideal distribution to use is the a. Normal distribution b. T circulation with 200 levels of freedom c. T circulation with 201 degrees of liberty d. T distribution with 202 levels of liberty Answer: a 13. Native a population that is normally distributed, a sample the 25 facets is selected and the standard deviation that the sample is computed.

For the interval estimate of (, the proper distribution to usage is the a. Normal distribution b. T circulation with 25 levels of flexibility c. T distribution with 26 levels of flexibility d. T distribution with 24 degrees of liberty Answer: d 14. The z value for a 97. 8% confidence interval estimation is a. 2. 02 b. 1. 96 c. 2. 00 d. 2. 29 Answer: d 15. The t value with a 95% confidence and also 24 levels of liberty is a. 1. 711 b. 2. 064 c. 2. 492 d. 2. 069 Answer: b 16. Together the sample dimension increases, the margin that error a. Rises b. Reduce c. Continues to be the exact same d. Boosts or decreases depending upon the dimension of the mean

The population standard deviation is well-known to same 4. 8. The 95. 44% trust interval because that the population mean is a. 15. 2 to 24. 8 b. 19. 200 come 20. 800 c. 19. 216 come 20. 784 d. 21. 2 to 22. 8 Answer: b 29. The sample size required to administer a margin the error that 2 or much less with a. 95 probability when the population standard deviation equals 11 is a. 10 b. 11 c. 116 d. 117 Answer: d 30. It is known that the population variance equates to 484. V a 0. 95 probability, the sample dimension that requirements to be taken if the preferred margin the error is 5 or less is a. 25 b. 74 c. 189 d. 75 Answer: d 31.

If we room interested in determining an interval estimate for (at 96. 6% confidence, the Z worth to use is a. 1. 96 b. 0. 483 c. 2. 12 d. 1. 645 Answer: c 41. Refer to Exhibit 8-2. The traditional error of the average is a. 22. 00 b. 96. 60 c. 4. 24 d. 2. 00 Answer: d 42. Describe Exhibit 8-2. If the trust coefficient is diminished to 0. 9, the traditional error of the median a. Will increase b. Will decrease c. Stays unchanged d. Becomes negative Answer: c 43. Describe Exhibit 8-2. The 96. 6% to trust interval because that (is a. 63. 00 come 67. 00 b. 60. 76 come 69. 24 c. 61. 08 to 68. 92 d. 60. 00 to 80. 00 Answer: b 44.

If past details shows a traditional deviation the 7 months, what dimension sample should be bring away so the at 95% to trust the margin of error will be 2 months or less? Answer: 48 7. A sample the 144 can be ~ of coffee showed an average weight of 16 ounces with a standard deviation of 1. 2 ounces. A. Construct a 68. 36% confidence interval for the mean of the population. B. Build a 97% trust interval for the typical of the population. C. Talk about why the answer in parts a and also b room different. Answers: a. 31. 88 to 32. 12 b. 31. 75 to 32. 25 c. Together the level of confidence increases, the confidence interval becomes wider. 8.

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A random sample that 121 checking accounts in ~ a bank showed one average everyday balance of \$280. The standard deviation that the populace is known to be \$66. A. Is it necessary to know anything around the form of the circulation of the account balances in stimulate to do an interval calculation of the average of every the account balances? Explain. B. Uncover the traditional error that the mean. C. Provide a point estimate of the populace mean. D. Construct a 80% confidence interval approximates for the mean. E. Build a 95% trust interval because that the mean. Answers: a. No, the sample is large and the conventional deviation that the population is known.. 6 c. 280 d. 272. 31 to 287. 69 e. 268. 24 to 291. 76 9. A arbitrarily sample that 53 monitorings was taken. The mean in the sample to be 90 v a variance of 400. A. Construct a 98% confidence interval because that (. B. Construct a 99% to trust interval because that (. C. Comment on why the 98% and also 99% to trust intervals are different. D. What would certainly you intend to take place to the confidence interval in component a if the sample size was increased? Be sure to define your answer. Answers: a. 83. 41 to 96. 59 b. 82. 65 to 97. 34 c. Together the level of trust increases, the confidence interval gets wider. D. Decrease due to the fact that the sampling error decreased. 0. A brand-new brand of coco bar is being market tested. Four hundred that the new chocolate bars were offered to consumers to try. The consumer were asked even if it is they liked or disliked the chocolate bar. You are provided their responses below. ResponseFrequency Liked300 Disliked100 400 a. What is the suggest estimate for the relationship of civilization who liked the chocolate bar? b. Build a 95% trust interval for the true ratio of civilization who chosen the cacao bar. C. V a. 95 probability, how huge of a sample demands to it is in taken to carry out a margin of error the 3% or less? Answers: a. 0. 75 b. 0. 71 come 0. 79 c. 801 1. If the typical deviation that the life time of washing makers is approximated to it is in 900 hours, how large a sample have to be bring away in bespeak to it is in 97% confident the the margin of error will certainly not exceed 100 hours? Answer: 382 12. The manager the a department keep wants to identify what relationship of people who go into the keep use the store’s credit cards for their purchases. What size sample need to he take it so the at 95% confidence the error will certainly not be an ext than 6%? Answer: 267 13. An Excel printout the the descriptive procedures of day-to-day checking account balances (in dollars) of customers of an initial Daisy financial institution is displayed below.

Develop a 95% to trust interval estimate for the median of the population of the checking balances. |Account Balance details | |Mean |4828. 29 | |Median |5115. 25 | |Mode |4976. 50 | |Standard Deviation |1143. 57 | |Sample Variance |1307763. 49 | |Kurtosis |8. 63 | |Skewness |-3. 06 | |Range |4968. 50 | |Minimum |600. 00 | |Maximum |5568. 50 | amount |173818. 50 | |Count |36. 00 | Answer: 4441. 382 come 5215. 198 14. Information regarding the price that a role of camera film (35 mm, 24 exposure) because that a sample the 12 cities an international is displayed below. Recognize a 95% confidence interval for the populace mean. |Price of Film information | | |Mean |5. 3667 | |Standard Error |0. 7409 | |Median |4. 8700 | |Standard Deviation |2. 666 | |Sample Variance |6. 5873 | |Kurtosis |4. 0201 | |Skewness |1. 8041 | |Range |9. 4100 | |Minimum |2. 7300 | |Maximum |12. 1400 | |Sum |64. 4000 | |Count |12. 0000 | Answer: 3. 736 to 6. 997