My civic duty is complete. I'll be at school all day. Feel free to come by before noon to say hi. I'll come by the MPR before you start. If you're studying tonight and want to e-mail a question, feel free.
Carne Asada Feast: May 31!!!
Monday, May 05, 2008
Sunday, May 04, 2008
sunday night
well, you're probably studying hard now. I definitely have to go do my civic duty at jury duty tomorrow. If there's anything that is stressing you out, feel free to drop me an e-mail!
mr d
mr d
Saturday, May 03, 2008
O-6
OK, folks. O-6 will challenge you. Here's the answers:
a) Ho: p = 0.5; Ha: p=/ 0.5
b) Conditions for a 1-prop z-test are NOT satisfied, because 8*0.5 = 4 which is a lot less than 10. In other words, the expected number of successes is too small.
c) To work around this problem, we use binomial pdf. We use p = 0.5, n = 8 and fill in the table:
0 0.00391
1 0.03125
2 0.10937
3 0.21875
4 0.27344
5 0.21875
6 0.10937
7 0.03125
8 0.00391
d) Since the test is two-sided, we see this this:
If x = 0 or 8, p = 2*0.0391 which is less than 5%
If x <= 1, then we add up the lower 2 and upper 2 and get 0.07312, which is greater than 5%
So 5% is not possible.
e) For the provided data, x = 2. So the p-value is 2*P(x <= 2) = 2*(0.003906 + 0.03125 + 0.109375) = 28.9% We would fail to reject and fail to find evidence of any difference between the two brands.
f) Increase sample size! It lowers the expected sd and enables us to more clearly see any differences that might exist between the two brands. sqrt(p*1-p/n) gets smaller!
That's a doozy of a problem, but hopefully this helps!
a) Ho: p = 0.5; Ha: p=/ 0.5
b) Conditions for a 1-prop z-test are NOT satisfied, because 8*0.5 = 4 which is a lot less than 10. In other words, the expected number of successes is too small.
c) To work around this problem, we use binomial pdf. We use p = 0.5, n = 8 and fill in the table:
0 0.00391
1 0.03125
2 0.10937
3 0.21875
4 0.27344
5 0.21875
6 0.10937
7 0.03125
8 0.00391
d) Since the test is two-sided, we see this this:
If x = 0 or 8, p = 2*0.0391 which is less than 5%
If x <= 1, then we add up the lower 2 and upper 2 and get 0.07312, which is greater than 5%
So 5% is not possible.
e) For the provided data, x = 2. So the p-value is 2*P(x <= 2) = 2*(0.003906 + 0.03125 + 0.109375) = 28.9% We would fail to reject and fail to find evidence of any difference between the two brands.
f) Increase sample size! It lowers the expected sd and enables us to more clearly see any differences that might exist between the two brands. sqrt(p*1-p/n) gets smaller!
That's a doozy of a problem, but hopefully this helps!
More??
OK folks, here's what I've done:
I'm more than happy to do more, but I will now switch to waiting for e-mail requests. I you want more answers (P or Q) or something else, just send me an e-mail:
mrmathman@(no-spam)gmail.com
Obviously, take out the no spam thing.
I'm more than happy to type up more answers if you're working hard and want them. Just drop me that e-mail and I'll put them up.
Good luck and happy studying to all!
- Flashcards powerpoint
- Name that green sheet website
- Answers to test O
- Name that green sheet answers for tests I through Q
I'm more than happy to do more, but I will now switch to waiting for e-mail requests. I you want more answers (P or Q) or something else, just send me an e-mail:
mrmathman@(no-spam)gmail.com
Obviously, take out the no spam thing.
I'm more than happy to type up more answers if you're working hard and want them. Just drop me that e-mail and I'll put them up.
Good luck and happy studying to all!
Friday, May 02, 2008
web site for inference
This web site loads slowly, but is pretty nifty:
Note: the wording on this website is more vague than the AP test. The AP test always asks for "a 95% confidence interval" if it wants an interval (or some other %). Also, the AP problems are longer, and thus have more information that will guide you to deciding what to do.
However, I think that after you 10 or so of these, you'll get used to the wording of this site and it will be good practice. If it is just always frustrating, switch to finding the tests and intervals in your notebook. Every released test (A, B, C,...) has at least one.
Note: this website includes prediction intervals, which you do not need to know.
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