# 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)