Unit 7 Notes 3 Margin of Error T-test

What is the z* for this problem?

Plug in all three variables we just identified. Use algebra to solve for n.

n = ____

State the variable we are studying in this question.

State the hypotheses for this question.

Let's do a One Sample T-test for Means.

Enter the list of differences in L1 in your calculator. What is $$\overline{x}_d$$ _?

What is the standard deviation of the sample?

Let's use a T-test. (Stat > Test > 2.T-test)

What is t?

Using the same calculator calculation, what is p?

Now that you have all the relevant information, what is your conclusion?

A sample of n students were asked for the average amount of money they spend in a day. The data resulted in a mean of $5.50 with a standard deviation of $2.45. If the margin of error was $0.31, how many students were in the sample? Round to the nearest whole student

A researcher wishes to estimate, within $25, the true mean amount of postage a community college spends each year. The standard deviation is known to be $80. If she wishes to be 95% confident in her estimate of the true mean amount of postage, how large a sample is necessary? Round to the nearest whole number

Suppose a department store wants to estimate within 2 years the true mean age of the customers in its contemporary apparel department. The department store manager assumes a standard deviation of 7.5 years. How large a sample is required to estimate the true mean age with 95% confidence?

Round to the nearest whole number

Complete the following statement about the change in size.

If you increase the size of your sample, the ME will . . . .

For a class project, a student in a statistics class surveys the monthly rent for 32 unfurnished one-bedroom apartments in Boston and finds the mean monthly rent to be $1400 with a standard deviation of $220.

Find the 95% confidence interval for the population mean Round to the nearest hundredth

A one sample t-test is conducted on Ho : μ = 81.6. The

sample has a sample mean = 84.1 , s = 3.1, n = 25, and α = .01.