Posted by **Anonymous** on Monday, July 19, 2010 at 5:36pm.

the average weekly earnings of a production worker were $424. to know if wages, on average, have gone up since that time. To test this, you sample 64 production workers, and determine that their average salary is $432.69, with a sample standard deviation of $33.90. Use a 0.05 level of significance .carry out test .

is it t test or z test ? how would we know

in this case is this one tailed or two tailed how can we conclude

- immediate help needed statistics one tailed hypo -
**MathGuru**, Monday, July 19, 2010 at 8:43pm
Usually you use z-tests when sample sizes are large (n is greater than

or equal to 30) whether or not you know the population standard deviation.

If you do not know the population standard deviation and have a small

sample (n < 30), then you can use t-tests.

You can determine the direction of the test by reading the problem. The problem says "gone up" which can be interpreted to mean "greater than" in your alternate hypothesis. If your alternate hypothesis shows a specific direction (like "greater than" or "less than"), then the test will be one-tailed. If you use "does not equal" in the alternate hypothesis (the results can be in either direction), then the test is two-tailed.

I hope this will help get you started.

- immediate help needed statistics one tailed hypo -
**Anonymous**, Tuesday, July 20, 2010 at 10:07am
i thought its a t test as it says sample standard deviation.

the main problem i get here is how to write null and alternative hypotheses as i cant decide whether it is one tailed or two tailed test.

- immediate help needed statistics one tailed hypo -
**MathGuru**, Wednesday, July 21, 2010 at 7:42pm
Ho: µ = $424 --->null hypothesis

Ha: µ > $424 --->alternative hypothesis

Since the alternative is showing a specific direction, the test is one-tailed.

- immediate help needed statistics one tailed hypo -
**Anonymous**, Thursday, July 22, 2010 at 11:29am
thank you

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