MATHEMATICS

8)  A random sample of  50 students has a test score average with a standard deviation of  11.4. Find the maximum error of estimate if c =  0.98. 8)  ________

A)  3.76 B)   0.53 C)   1.61 D)   1.58

 

SHORT ANSWER.  Write the word or phrase that best completes each statement or answers the question.

9)  In a recent study of  71 eighth graders, the mean number of hours per week that they watched television was  18.7 with a standard deviation of  5.8 hours.

 

a) Find the  98% confidence interval of the mean.

b) If the standard deviation is doubled to  11.6, what will be the effect on the confidence interval? 9)  ______________

 

MULTIPLE CHOICE.  Choose the one alternative that best completes the statement or answers the question.

10)  A random sample of 150 students has a grade point average with a mean of 2.86 and with a standard deviation of 0.78. Construct the confidence interval for the population mean, m, if c = 0.98. 10)  _______

A) (2.71, 3.01) B)  (2.51, 3.53) C)  (2.43, 3.79) D)  (2.31, 3.88)

 

11)  A random sample of 40 students has a test score with  overbar(x) = 81.5 and s = 10.2. Construct the confidence interval for the population mean, m if c = 0.90. 11)  _______

A) (78.8, 84.2) B)  (51.8, 92.3) C)  (66.3, 89.1) D)  (71.8, 93.5)

 

12)  A random sample of 40 students has a mean annual earnings of $3120 and a standard deviation of $677. Construct the confidence interval for the population mean, m if c = 0.95. 12)  _______

A) ($2910, $3330) B)  ($210, $110)

C) ($4812, $5342) D)  ($1987, $2346)

 

13)  A random sample of 56 fluorescent light bulbs has a mean life of 645 hours with a standard deviation of 31 hours. Construct a 95% confidence interval for the population mean. 13)  _______

A) (636.9, 653.1) B)  (539.6, 551.2)

C) (112.0, 118.9) D)  (712.0, 768.0)

 

14)  A group of 49 randomly selected students has a mean age of 22.4 years with a standard deviation of 3.8. Construct a 98% confidence interval for the population mean. 14)  _______

A) (21.1, 23.7) B)  (20.3, 24.5) C)  (19.8, 25.1) D)  (18.8, 26.3)

 

15)  A group of 40 bowlers showed that their average score was 192 with a standard deviation of 8. Find the 95% confidence interval of the mean score of all bowlers. 15)  _______

A) (189.5, 194.5) B)  (186.5, 197.5)

C) (188.5, 195.6) D)  (187.3, 196.1)

 

16)  In a random sample of 60 computers, the mean repair cost was $150 with a standard deviation of $36. Construct a 99% confidence interval for the population mean. 16)  _______

A) ($138, $162) B)   ($18, $54) C)  ($238, $274) D)  ($537, $654)

 

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