Recent content by WHB3

I finally figured it out, guys. The Z value is between +-.848 which, assuming a normal distribution, gives P(.48<Xbar<.52) =.6046, which I think is correct. Thanks for the help!

In computing P(.48<Xbar<.52), I come up with, +-.02/(sqrt(150)times(1/((sqrt(12))=+-.00565; I don't think that these are the correct limits for the integral.

Thanks, but I am stilll stuck. The limits I am coming up with are +_.006 which don't result in the book answer which is .6046.

It looks like the mean and variance of a uniformly distributed single random variable over the interval of (0,1) is .5 and 1/12 respectively. However, I am still stumped on how to use this information to compute the required probability. Any further suggestions on how to get un-stumped?

Homework Statement What is the probability that the average of 150 random points from the interval (0,1) is within .02 of the midpoint of the interval? Homework Equations The Attempt at a Solution I need to determine P(.48<((X1...X150)/150)<.52). I think I need to compute the...

After several more attempts (and re-reading your analysis), I think I finally solved the problem. Thanks, Lanedance!

I see what you're saying, that the sample means should reflect the multiple of the sample size. However, don't I still end up with a denominator equal to the square root of minus 1/3?

Homework Statement Vicki owns two separtment stores. Delinquent charge accounts at store #1 show a normal distribution, with mean $90 and std. deviation $30, whereas at store #2, they show a normal distribution with mean $100 and std. deviation $50. If 10 delinquent accounts are selected...

No need to respond, guys. I have found the error of my ways. I forgot that the std Error equals the std deviation divided by the sqr. root of the sample size. Working with that would have brought me to the Probability = 1-I(1.58) = 1-1.9429 =.0571. Thanks, anyway!

Homework Statement The distribution of the IQ of a randomly selected student from a certain college is N(110,16). What is the probability that the average of the IQ's of 10 randomly selected students from this college is at least 112? Homework Equations I think we need P(Sample Mean...

I still need an answer to this problem, so if anyone knows what I'm doing wrong here, I would appreciate the help.

Thanks for the help (and patience), guys; I finally understand it.

When I try to factor this equation using the formula we learned in high school, I get -2Cov(X,Y) +-radical(4Cov^2(X,Y)-4VarXVarY)divided by 2VarX. Since everything under the radical goes to zero, I am left with -2Cov(X,Y)/2VarX = Cov(X,Y)/VarX; this is not the answer I should be...

Thanks for the help! Your answer would indicate that it isn't necessary to compute any derivatives to determine the function M. Is that correct? Also, do you have any idea how to go about computing the probability mass fctn p(i)?

Homework Statement Suppose that for a random variable X, E(X^n)=2^n, for n=1,2,3,...through infinity. Calculate the moment generating function (Mx(t)) and the probability mass function (p(i)). Homework Equations The Attempt at a Solution It seems as though, letting t=0...