MATHEMATICS

32)  A manufacturer receives an order for fluorescent light bulbs. The order requires that the bulbs have a mean life span of  850 hours. The manufacturer selects a random sample of 25 fluorescent light bulbs and finds that they have a mean life span of  845 hours with a standard deviation of 15 hours. Test to see if the manufacturer is making acceptable light bulbs. Use a 95% confidence level. Assume the data are normally distributed. 32)  _____________

 

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

33)  Construct a 95% confidence interval for the population mean, m. Assume the population has a normal distribution. A sample of 20 college students had mean annual earnings of $3120 with a standard deviation of $677. 33)  _______

A) ($2803, $3437) B)  ($1324, $1567)

C) ($2135, $2567) D)  ($2657, $2891)

 

34)  Construct a 90% confidence interval for the population mean, m. Assume the population has a normal distribution. A sample of 15 randomly selected students has a grade point average of 2.86 with a standard deviation of 0.78. 34)  _______

A) (2.51, 3.21) B)  (2.41, 3.42) C)  (2.37, 3.56) D)  (2.28, 3.66)

 

35)  Construct a 95% confidence interval for the population mean, m. Assume the population has a normal distribution. A sample of 25 randomly selected students has a mean test score of 81.5 with a standard deviation of 10.2. 35)  _______

A) (77.29, 85.71) B)  (56.12, 78.34)

C) (66.35, 69.89) D)  (87.12, 98.32)

 

36)  Construct a 95% confidence interval for the population mean, m. Assume the population has a normal distribution. A random sample of 16 fluorescent light bulbs has a mean life of 645 hours with a standard deviation of 31 hours. 36)  _______

A) (628.5, 661.5) B)  (876.2, 981.5)

C) (531.2, 612.9) D)  (321.7, 365.8)

 

37)  Construct a 99% confidence interval for the population mean, m. Assume the population has a normal distribution. A group of 19 randomly selected students has a mean age of 22.4 years with a standard deviation of 3.8 years. 37)  _______

A) (19.9, 24.9) B)  (16.3, 26.9) C)  (17.2, 23.6) D)  (18.7, 24.1)

 

38)  Construct a 98% confidence interval for the population mean, m. Assume the population has a normal distribution. A study of 14 bowlers showed that their average score was 192 with a standard deviation of 8. 38)  _______

A) (186.3, 197.7) B)  (222.3, 256.1)

C) (328.3, 386.9) D)  (115.4, 158.8)

 

39)  Construct a 90% confidence interval for the population mean, m. Assume the population has a normal distribution. In a recent study of 22 eighth graders, the mean number of hours per week that they watched television was 19.6 with a standard deviation of 5.8 hours. 39)  _______

A) (17.47, 21.73) B)  (18.63, 20.89)

C) (5.87, 7.98) D)  (19.62, 23.12)

 

40)  A random sample of 10 parking meters in a beach community showed the following incomes for a day. Assume the incomes are normally distributed.

 

$3.60  $4.50  $2.80  $6.30  $2.60  $5.20  $6.75  $4.25  $8.00  $3.00

 

Find the 95% confidence interval for the true mean. 40)  _______

A) ($3.39, $6.01) B)  ($2.11, $5.34)

C) ($4.81, $6.31) D)  ($1.35, $2.85)

 

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