You work for a charitable organization and you want to see whether the people who donate to your organization have an average age above 40 years. You get a random sample of 219 donors and the value of...

You work for a charitable organization and you want to see whether the people who donate to your organization have an average age above 40 years. You get a random sample of 219 donors and the value of the sample mean age is 42 years. The value of the sample standard deviation is 17 years. The executive director wants you to be 95% confident in your results.

1. State in statistical terms the null and alternative hypotheses.


2. Determine the critical value(s).


3. Compute the test statistic.


4. Make a decision about the hypotheses (which hypothesis is correct?)


5. Are donors older than 40 years old?

I need help with #2, 3, and 4. Though I worked 2, I'm still confused about it.

I got 1.7410 for 3

And 1.7410>1.6519 for 4.

I am not sure if I'm right. Help!