52The margin oferror for the population mean, assuming is known, is: z multiplie

Question

52The margin oferror for the population mean, assuming is known, is: z multiplied by the population standard deviation A) C) multiplied by the standard deviation of the sample mean D) z multiplied by the sample mean 53. The: value for a 95% confidence interval for the population mean with known is: A) 2.05 B) 1.96 C) 2.17 D) 1.60 a confidence interval by; A) lowering the confidence level or decreasing the sample size B) increasing the confidence level or decreasing the sample size C) lowering the confidence level or increasing the sample size D) increasing the confidence level or increasing the sample size 55. To decrease the width of a confidence interval, we should always prefer to: A) B) C) D) lower the confidence level increase the confidence level increase the sample size decrease the sample size

Explanation / Answer

52) The margin of error is computed as:

MOE = z*SE

where SE is the standard deviation of the sample mean. Therefore C is the required answer here.

53) From the standard normal tables, we get:

P( Z < 1.96 ) = 0.975

Therefore due to symmetry, we get:

P( -1.96 < Z <1.96 ) = 0.95

Therefore B is the correct answer here.

54) The confidence interval width depends on the margin of error which is inversely proportional to the square root of the sample size. Therefore the width of confidence interval could be decreased by lowering the confidence level or increasing the sample size.

Therefore C is the correct answer here.

55) To decrease the confidence interval width we should prefer to increase the sample size, so that our confidence level is not affected. Therefore C is the correct answer here.

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