Blog

Suppose that you were interested in conducting a survey of Floridians and asking if they approved of the President. Suppose that you have no idea what this proportion would be, but at the end of the study you want to calculate a 95% confidence interval with a 0.025 margin of error. Find the sample size needed.

A sample of 2,419 US residents were asked if they considered their home “very clean” right now. The 95% confidence interval was (0.0146. 0.0259). Is the following interpretation of the confidence interval correct? “We are 95% confident that the sample proportion of Americans that consider their home very clean is between 0.0146 and 0.0259.”  

Suppose that you took a sample of 20 students at UF and asked them how many minutes they exercised yesterday. Suppose that you wanted to make a 90% confidence interval for the population mean. What value would you use for t?

The average height of men in Cameroon is 1.706 meters with a standard deviation of 0.154 m. Height is approximately normally distributed. Suppose that a sample of 35 men is selected, find the range of the central 99.7% of sample mean heights?

Suppose that you wanted to estimate the population proportion of students at UF that approved of the job that what congress was doing. You decided to take a sample, but you needed to determine what size sample to take. You were uncertain what this proportion would be. You wanted to be 95% confident and to have a margin of error of 0.035. What size sample would you need?

In the year 2015, according to salary.com, nurses in Los Angelos have an average annual salary of $85,693. The standard deviation is about 6,000 dollars. The distribution of salaries is right skewed. Suppose that a sample of 20 nurses is taken from Los Angelos. What is the approximate sampling distribution of the sample mean?  

For a confidence interval for the population mean, if you increase the confidence level, what happens to the width of the interval (everything else remains the same)?

A survey of 20 randomly selected people from Gainesville were asked if they planned on purchasing a new house in the next year. Out of 20 people, 5 said yes. Can you make a 95% confidence interval for the population proportion?

For a 99% confidence interval for the population mean, what value of t would you use? n = 17

Suppose that you wanted to conduct a survey and sample UF students. Suppose you wanted to ask them how many of them planned on getting a meal plan for the Fall semester. In previous year, the proportion of students with a meal plan has been around 0.40. Suppose you want to be 95% confident and have a margin of error of 0.05. What size sample do you need?