B. the margin of error of u is ? (round to one decimal place as needed.) C. inte

Question

B. the margin of error of u is ? (round to one decimal place as needed.)

C. interpret the results. pick 1,2,3 or 4 below.

1. with 98% confidence it can be said that the population mean commute time is between the bounds of the confidence interval.
2. with 98% confidence it can be said that the commute time is between the bounds of the confidence interval.
3. it can be said that 98% of people have a commute time between the bounds of the confidence interval.
4. if a large sample of people are taken approximately 98% of them will have commute times between the bounds of the confidence interval.

In a random sample of 21 people, the mean commute time to work was 31.9 minutes and the standard deviation was 7.3 minutes. Assume the population is normally distributed and use a t-distribution to construct a 99% confidence interval for the population mean . What is the margin of error of ? Interpret the results. The confidence interval for the population mean is OD Round to one decimal place as needed.)

Explanation / Answer

B. Margin of error of population mean = Critical Test statistic * standard error of sample mean

Critical Test statistic = t20,0.01 = 2.8453

standard error of sample mean = s/ sqrt(n) = 7.3 /sqrt (21) = 1.593

so Margin of error = 2.8453 * 1.593 = 4.533 minutes ~ 4.5 minutes

99% confidence interaval of = x + margin of error = 31.9 +- 4.533

= (27.4 mins , 36.4 mins)

C. Answer ; with 98% confidence it can be said that the population mean commute time is between the bounds of the confidence interval.

OPtion 1 is correct.

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