# Mathematics

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

29) Construct a 98% confidence interval for the population mean, m. Assume the population has a normal distribution. A random sample of 20 college students has mean annual earnings of $3480 with a standard deviation of $668. 29) _____________

30) Construct a 95% confidence interval for the population mean, m. Assume the population has a normal distribution. In a random sample of 26 computers, the mean repair cost was $160 with a standard deviation of $34. 30) _____________

31) a) Construct a 95% confidence interval for the population mean, m. Assume the population has a normal distribution. In a random sample of 26 computers, the mean repair cost was $174 with a standard deviation of $37.

b) Suppose you did some research on repair costs for computers and found that the standard deviation is sigma = 37. Use the normal distribution to construct a 95% confidence interval for the population mean, m. Compare the results. 31) _____________

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)

41) The grade point averages for 10 randomly selected high school students are listed below. Assume the grade point averages are normally distributed.

2.0 3.2 1.8 2.9 0.9 4.0 3.3 2.9 3.6 0.8

Find a 98% confidence interval for the true mean. 41) _______

A) (1.55, 3.53) B) (0.67, 1.81) C) (2.12, 3.14) D) (3.11, 4.35)

42) A local bank needs information concerning the checking account balances of its customers. A random sample of 15 accounts was checked. The mean balance was $686.75 with a standard deviation of $256.20. Find a 98% confidence interval for the true mean. Assume that the account balances are normally distributed. 42) _______

A) ($513.17, $860.33) B) ($238.23, $326.41)

C) ($326.21, $437.90) D) ($487.31, $563.80)

43) When 475 college students were surveyed, 125 said they own their car. Find a point estimate for p, the population proportion of students who own their cars. 43) _______

A) 0.263 B) 0.737 C) 0.357 D) 0.208

44) A survey of 100 fatal accidents showed that 11 were alcohol related. Find a point estimate for p, the population proportion of accidents that were alcohol related. 44) _______

A) 0.11 B) 0.89 C) 0.124 D) 0.099

45) A survey of 500 non-fatal accidents showed that 118 involved the use of a cell phone. Find a point estimate for p, the population proportion of accidents that involved the use of a cell phone. 45) _______

A) 0.236 B) 0.764 C) 0.309 D) 0.191

46) A survey of 250 households showed 37 owned at least one gun. Find a point estimate for p, the population proportion of households that own at least one gun. 46) _______

A) 0.148 B) 0.852 C) 0.174 D) 0.129

47) A survey of 2490 golfers showed that 347 of them are left-handed. Find a point estimate for p, the population proportion of golfers that are left-handed. 47) _______

A) 0.139 B) 0.861 C) 0.162 D) 0.122

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

48) When 385 college students were surveyed, 160 said they own their car. Construct a 95% confidence interval for the proportion of college students who say they own their cars. 48) _____________

49) A survey of 600 non-fatal accidents showed that 166 involved the use of a cell phone. Construct a 99% confidence interval for the proportion of fatal accidents that involved the use of a cell phone. 49) _____________

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

50) A survey of 100 fatal accidents showed that 52 were alcohol related. Construct a 98% confidence interval for the proportion of fatal accidents that were alcohol related. 50) _______

A) (0.404, 0.636) B) (0.120, 0.340)

C) (0.560, 0.580) D) (0.880, 0.900)

51) A survey of 250 households showed 62 owned at least one gun. Construct a 90% confidence interval for the proportion of households that own at least one gun. 51) _______

A) (0.203, 0.293) B) (0.103, 0.189)

C) (0.369, 0.451) D) (0.683, 0.712)

52) A survey of 2450 golfers showed that 281 of them are left-handed. Construct a 98% confidence interval for the proportion of golfers that are left-handed. 52) _______

A) (0.100, 0.130) B) (0.203, 0.293)

C) (0.369, 0.451) D) (0.683, 0.712)