Recent content by lotsofmoxie

Is the answer zero? I can post my reasoning if its forum policy or something

Err sorry, typo. It's 1/4. so we get P(X>275) >= 1-cdfnorm[(275-275*p)/(sqrt(n/4)) what about the p in the numerator? Are we trying to get a lower or upper bound?

Hmmm. So the max value of p(1-p) (if I'm using p = probability that a given person answers yes to the question) would be 1/2. So I can plug that into my z value?

I'm really not seeing how it is possible to do this problem without knowing the probability that a particular person answers yes or no. You need this to calculate an exact Z value, and how large or small it is makes a huge difference to the answer - from what I can see, the central limit...

I'm really not seeing how it is possible to do this problem without knowing the probability that a particular person answers yes or no. You need this to calculate an exact Z value, and how large or small it is makes a huge difference to the answer. My gut tells me that we are just supposed to...

What can we say about the population distribution besides it is binomial and about the sample distribution besides its average is approximately normal with large enough n?

Homework Statement Assume five hundred people are given one question to answer - the question can be answered with a yes or no. Let p =the fraction of the population that answers yes. Give an estimate for the probability that the percent of yes answers in the five hundred person sample is...

****. I wrote my integral down messily and I mistook a u for a 4 in the bounds and never caught my mistake later. It should be ∫∫1/4*5e^(-5t)dtdu where inner integral is over (u, infinity) and outer is over (0,4), which gives the same answer as using your method above. I really hate myself...

I got 0.04999999989. I don't see where I went wrong when I did the integral - it didn't seem too messy when I did it putting the numerical values in first, but for some reason it is wrong. I tried plugging it into wolfram alpha, and the answer it gave was the same as the one I calculated, so...

Wait, the problem you just explained was part e, right? I was trying to do d).

So starting with the inner integral ∫1/4*5e^(-5t)dt pull out the 1/4 so we have 1/4 ∫5e^(-5t)dt over (4,oo) use a substition w=-5t, dw=-5dt--->dt=dw/-5 so the integral becomes 1/4 ∫5e^(w)dw/-5 over (some interval that doesn't matter because I'll convert it back to t before using them) =-1/4...

Gah Ok. ∫∫1/4*5e^(-5t)dtdu where inner integral is over (4, infinity) and outer is over (0,4) Is this the integral you are starting with?

Thank you for responding. It makes sense now. I'm getting 1-1/e^20 for d). Is this correct?

especially on a, b, c I'm not sure if I'm doing it right (my answer for b seems intuitively too small).