11In standard normal distribution the means is always (Points : 3)



2.  The area under the standard normal curve is (Points : 3)



3. 3.If Larry gets a 70 on a physics test where the mean is 65 and the standard deviation is 5.5.8, where does he stand in relation to his classmates? (Points : 3)



4.  In a normal distribution with mu = 25 and sigma = 3, what number corresponds to z = -3? (Points : 3)



5.  Let’s assume you have taken 100 samples of size 49 each from a normally distributed population. Calculate the standard deviation of the sample means if the population’s variance is 16. (Points : 3)



6.  The area to the left of ‘z’ is 0.9976. What z-score corresponds to this area? (Points : 3)



7.  Find P(9 < x < 22) when mu = 20 and sigma = 5. (Points : 3)



8.  What is the critical z-value that corresponds to a confidence level of 88%? (Points : 3)



9.  Compute the population mean margin of error for a 95% confidence interval when sigma is 4 and the sample size is 36. (Points : 3)



10.  A standard IQ test has a mean of 98 and a standard deviation of 16. We want to be 90% certain that we are within 8 IQ points of the true mean. Determine the sample size. (Points : 3)



11.  A private medical clinic wants to estimate the true mean annual income of its patients. The clinic needs to be within $200 of the true mean. The clinic estimates that the true population standard deviation is around $1,300. If the confidence level is 95%, find the required sample size in order to meet the desired accuracy. (Points : 6)



112. An auditor wants to estimate what proportion of a bank’s commercial loan files are incomplete. The auditor wants to be within 7% of the true proportion when using a 95% confidence level. How many files must the auditor sample? No estimate of the proportion is available, so use 0.5 for the population proportion. (Points : 6)




I Interpret a 90% confidence interval of (4.355, 4.445) for a population mean.



A nursing school wants to estimate the true mean annual income of its alumni. It randomly samples 200 of its alumni. The mean annual income was $55,200 with a standard deviation of $1,500. Find a 95% confidence interval for the true mean annual income of the nursing school alumni. Write a statement about the confidence level and the interval you find


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