that o = 48 hours, how large a sample be needed so that one will be able to assert with 90% confidence that the sample mean is off by at most 10 hours?
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- Find a 95% confidence interval for H given that x = 75.8, s = 19, n = 10.The researcher took a random sample of 50 residents and found that the mean height of men is 175cm. Suppose that the team is made aware of the fact that the distribution of heights is distributed normally. 1, The sample median is an unbiased estimate of the mean height of men. Is the following statement about the estimator true? 2, Determine whether or not the median or mean is an efficient estimator of the population median.Sam computed a 95% confidence interval for mean from a specific random sample. His confidence interval was 10.1< mean< 12.2. He caims that the probability that mean is in this interval 0.95. What os wrong with his claim?
- A random sample of n=16 scores is obtained from a population with a standard deviation of 16. If the sample mean is greater than 8 points greater than the population mean, what is the z-score for the sample mean?Random samples of 324 are taken from a large population and studied. It was found that x = 7.41. If 22.96% of all sample means were greater than 288.6834. What is μ? μ =How large a sample must be taken to be 99% confident that the estimate of the average time of long-distance calls is within 5 minutes of the true average time of long-distance calls of all customers? A previous study indicated that the standard deviation for long-distance calls is 30 minutes.
- A doctor wants to estimate the mean HDL cholesterol of all 20- to 29-year-old females. How many subjects are needed to estimate the mean HDL cholesterol within 4 points with 99% confidence assuming s=10.7 based on earlier studies? Suppose the doctor would be content with 95% confidence. How does the decrease in confidence affect the sample size required?A doctor wants to estimate the mean HDL cholesterol of all 20- to 29-year-old females. How many subjects are needed to estimate the mean HDL cholesterol within 2 points with 99% confidence assuming s=13.4 based on earlier studies? Suppose the doctor would be content with 95% confidence. How does the decrease in confidence affect the sample size required?A researcher wishes to estimate the true proportion of all speeders who exceed the posted speed limit on a particular stretch of road in the Canyonlands National Park where there are frequent accidents. How large should the sample be so that with 91 percent confidence, the sample proportion will not differ from the true proportion by more than 0.261?z = n ⩾
- In order to have the standard error of the mean be 6, one would need to take a sample of size from a normally distributed population with a standard deviation of 42How large a sample must be taken to be 99% confident that the estimate of the average time of long-distance calls is within 3 minutes of the true average time of long-distance calls of all customers? A previous study indicated that the standard deviation for long-distance calls is 20 minutes.Suppose scores on exams in statistics are normally distributed with an unknown population mean and a population standard deviation of three points. A random sample of 36 scores is taken and gives a sample mean score of 68. Find a 90% confidence interval estimate for all the mean score on all exams or the true (population) mean of statistics exam scores. Use the format xx.xxx