```Question 137871
Does anyone know what the formula for the z test for proportions is???
Most textbooks use a t-test on proportion problems and on mean problems
where n is less than 30.
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Z-values are critical values and are test statistics for one and two
sample proportions tests.
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I have a few more questions that I really need help with solving.
1) Joan moves into her apartment and wants to purchase a new couch. She wants to determine if there is any difference between the average cost of couches at two different stores. Test the hypothesis that there is no difference at a=0.05.
_ Store 1 Store 2
x \$650 \$730
O \$61 \$78
n 24 21
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What are your "x" and "o" numbers.
The "x" looks like a sample mean
The "o" might be a sample standard deviation.
But it's hard to be sure.
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2) Stating that the area under the curve between z=0 and z=1.00 is 0.3413 is the same as stating that the PROBABILITY of selecting any z value between 0 and 1.00 is 0.3413.
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3) A regression line was calculated as y = 9.7 -3.2x. The slope of this line is -3.2. True or false??
Ans: true
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4) The ________________ are the number of values that are free to vary after sample statistic has been computed.
Sounds like degrees of freedom but I am not sure.
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Cheers,
Stan H.

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