Question

sample of size n=44 drawn from a population with σ=7.5 has x¯=17.9. Find a 92% confidence interval for the population mean by completing each of the following in turn. Round all your answers to the nearest hundredth.

x¯=

c=

zc=

E=

Confidence interval is ( , )

E = 1.97866819879157

The systolic blood pressure (SBP) of a certain population is normally distributed with standard deviation 6 mmHg. A sample of 24 members of this population was found to have an average SBP of 122 mmHg. Find a 90% confidence interval for the population mean. Round the endpoints to the nearest integer.

Confidence interval is ( , )

The average starting salaries for 48 graduates with a certain major was $42061. The standard deviation for all graduates with that major was $8318. Give the 90% confidence interval for the population mean. Round the endpoints to the nearest dollar, and do not put commas in your numbers.

Confidence interval: ( , )

The diameter of the twelve-penny common nails made by ’Snails!, Inc., is normally distributed with standard deviation 0.004 in. A sample of 34 such nails was found to have a mean diameter of 0.127 in. Find a 92% confidence interval for the mean diameter of all such nails. Round the endpoints to five decimal places.

Confidence interval is ( , )

390 confidence intervals, each having a 95% level of confidence, were computed for a population mean μ, about how many of the intervals can be expected to contain μ?  (Your answer will be an integer, of course.)

300 confidence intervals, each having a level of confidence of 91%, were computed for a population mean μ, approximately how many of the intervals would be expected to contain μ?  (Round your answer to the nearest integer.)

Answer 1