(10) A researcher wishes to estimate the number of households with two computers. How large a sample is needed in order to be 99% confident that the sample proportion will not differ from the true proportion by more than E = 3%? A previous study indicates that the proportion of households with two computers is 20%.
A) 966 B) 1180 C) 1474 D) 5
(11) Determine the point estimate of the population mean and margin of error for the confidence interval with lower bound 17 and upper bound 27.
A) x̄ = 22, E = 10 B) x̄ = 22, E = 5 C) x̄ = 17, E = 10 D) x̄ = 27, E = 4
(12) Construct a 95% confidence interval for the population mean, μ. Assume the population has a normal distribution. A sample of 20 part-time workers had mean annual earnings of $3120 with a standard deviation of $677. Round to the nearest dollar.
A) ($2135, $2567) B) ($1324, $1567) C) ($2803, $3437) D) ($2657, $2891)
(13) Construct a 90% confidence interval for the population mean, μ. Assume the population has a normal distribution. A sample of 15 randomly selected math majors has a grade point average of 2.86 with a standard deviation of 0.78. Round to the nearest hundredth.
A) (2.51, 3.21) B) (2.41, 3.42) C) (2.37, 3.56) D) (2.28, 3.66)
(14) Determine the sample size required to estimate the mean score on a standardized test within 4 points of the true mean with 90% confidence. Assume that s = 15 based on earlier studies.
A) 1 B) 39 C) 139 D) 70