The Chancellor wants you to calculate the sample size needed with a margin of error of 15, 99% confidence, and a population standard deviation of 22.

The sample mean X is to be used to estimate the mean u of a normal distribution with standard deviation 4 inches. How large a sample should be taken in order chat, with 90% probability, the estimate will be in error by at most one-half inch?

A medical statistician wants to estimate the average weight loss of people who are on a new diet plan. In a preliminary study, he guesses that the standard deviation of the population of weight loss is about 8 pounds. How large a sample should he take to estimate the mean weight loss to within 4 pounds, with 97% confidence? Sample Size =

You want to estimate the mean amount of time Internet users spend on Facebook each month. How many Internet users must be surveyed in order to be 90% confident that your sample mean is within 10 minutes of the population mean? Based on results from a prior survey, assume that the standard deviation of the population of monthly times spent on Facebook is 210 minutes.

Loretta, who turns 91 this year, has heard that the mean systolic blood pressure among the elderly is 120 millimeters of mercury (mm Hg), but she believes that the actual value is higher. She bases her belief on a recently reported study of 19 randomly selected, elderly adults. The sample mean systolic blood pressure of the adults in the study was 121 mm Hg , and the sample standard deviation was 20 mm Hg. Assume that the population of systolic blood pressures of elderly adults is normally distributed. Based on the study, at the 0.1 level of significance, can it be concluded that μ , the mean systolic blood pressure among elderly adults, is greater than 120 mm Hg? Perform a one-tailed test. Then complete the parts below. Carry your intermediate computations to three or more decimal places and round your answers as specified in the table. (a) State the null hypothesis H0? and the alternative hypothesis H1? . H0:? H1:? (b) Determine the type of test statistic to…

Yane is a researcher who studies bacteria. They are trying to ascertain the mean lifespan for a bacteria species. It is believed that the standard deviation of their lifespan is o = 4 hours. They would like to estimate the mean lifespan for this species of bacteria to within a margin of error of 0.45 hours at a 99% level of confidence. What sample size should they gather to achieve this? Remember your answer must be a whole number. n= bacteria

There is a new medication for diabetes, fifteen participants take the medication for fifteen days. The average blood glucose before taking the medication was 155 (population mean). The average blood glucose after taking the medication is 110. The standard deviation for the average glucose after taking the medication is 4.6. You want to evaluate if there is statistical evidence that there is a reduction in the mean glucose after taking the medication for 15 days. You must conduct a t-test. What is the t-statistic?

You would like to make an interval estimate of a population mean from a sample of size 25. Assume the population standard deviation is 6. Assuming 98% Confidence, what is the margin for error for the estimate.

How can get the standard deviation within the measures of dispersion or variability ?