Proving he makes over 80%

I had a problem that said the following:

1) A basketball player claims to be able to make over 80% of her free throws. If she shoots 80 and makes 70, does this support her cliam at the 1% significance level?

I did the problem and concluded that I couldn't support her claim that she makes over 80%.

Now I am asked to find out how many she would have to make in order to prove that she actually does make over 80% at the .01 significance level.

One other problem:

2) I am asked to verify that my exam (77%), quiz (90%), lab(101%), and homework (93%) percents are accurate. How would I approach that? Do I need more info than just the percents?

Thanks for any tips.

dboybbfs said:

1) A basketball player claims to be able to make over 80% of her free throws. If she shoots 80 and makes 70, does this support her cliam at the 1% significance level?

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I'm a bit surprised by that.

70/80 = 0.875

Sample Size = 80

I think I would check that again. What are your intermediate results?

Hypotheses?
Critical Values?
Sample Variance?

I tried the sample size for proportion p which is shown below. I got 8 though and obviously that is wrong. Am I doing the margin of error formula wrong or am I just completly lost?

"p-hat" = 0.875
"q-hat" = 0.125
sigma = 0.01
n = 80

E = (2.575)(sqrt[0.875x0.125/80]) = 0.1

n = (2.575^2)(0.875)(0.125)/0.1 = 7.25

...or, rounding up, n = 8

does this support her cliam at the 1% significance level?

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What are you doing? This looks like a "Test of Hypothesis" problem. Why are you trying to calculate a sample size that is already stated as 80?

For the record:

1) Your allowable error should be squared. This will help you find "80".
2) You have not stated any hypothesis other than what is in the problem statement.

Are you SURE you're thinking about this correctly?

This is a hypothesis test.

I am only stating what my instructer gave me.

dboybbfs said:

This is a hypothesis test.
I am only stating what my instructer gave me.

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You made a TERrible typo: instrucTER should be instrucTOR :roll:

Speaking of hypotheses, I'll make one that says you are a professor... :lol:

Meanwhile, back on the farm...

Have you hypotheses? You should have a Null and an Alternative. What are they?

Problem was do today. I don't exactly remember what I wrote but I remember I got 74 as my answer.

My instrucTER wouldn't accept any late homework.

I have great anticipation, waiting for those hypotheses.