Question

HELP! Last question! Two sample z-test?

There are 58 men and 64 women in a class. We want to test whether the women in the class have higher grades than the men in the class. The average grade for women is 92.1 and the average grade for men is 87.4. Based on previous courses, we know that the standard deviation of grades is 6.8 for both men and women.



Conduct a two-sample z-test using alpha=.05. What is the z-statistic you obtain for this test? what should you conclude about the relationship between the scores of men and women in the class?



Clearly state your null and alternative hypotheses. Also state what statisical decision should be made (accept/reject) and what this decision means in practical terms (i.e. with regard to grades in the class).

Answer 1

does this look like what you are doing?

Answer 2

I can't really follow that picture

Answer 3

@cruffo , that's how I'm doing them. ;-)

Answer 4

is that with a ti-83?

Answer 5

I use TI-84, but they are the same.

Answer 6

Ah i'm confused as to what that is showing I got the same thing on my caluculator

Answer 7

mine is the TI-84 plus smartview (on the pc)

Answer 8

This is easy enough to do without a calculator, though.

Answer 9

So 3.81 is the z-statistic?

Answer 10

yes.

Answer 11

I have a really hard time coming up the hypothesis in words idk why thats my weakness lol

Answer 12

a z-score of 3.81 pretty much means a 0 probability right?

Answer 13

Close enough to 0 for this scenario. It is definitely way below the α

Answer 14

For the hypotheses, consider that you are trying to see if there is a difference between men and women - difference means subtraction.
A proper null would be no difference, and an alternative would be women > men, since that is the point of the test.

Answer 15

Another way to state the alternative is that the difference between women and men is greater than zero.

Answer 16

Okay thats what I was thinking. And the probabily of the scores of men being greater than women is almost 0?

Answer 17

So i can reject the null hypothesis

Answer 18

Yes, you can reject the null because the probability, p < 0.05.

Sorry, actually for the null. women < men is better since it is a one-sided test.

Answer 19

http://stattrek.com/hypothesis-test/difference-in-means.aspx?Tutorial=AP