40. A 90% confidence interval is to be created to estimate the proportion of television viewers in a certain area who favor among the broadcast of the late weeknight news to an hour earlier than it is currently. Initially, the confidence interval will be created using a simple random sample of 9,000 viewers in the area. Assuming that the sample proportion does not change, what would be the relationship between the width of the original confidence interval and the width of a second 90% confidence interval that is created based on a sample of only 1,000 viewers in the area?

I asked this question before, and got an answer, but I have a question about the response that was given.  The original question was: For an initial investment of 100, an investment yields returns of X1 and X2, where X1 and X2 are independent normal random variables with mean 60 and variance 25.  What is the probability that the rate of return of this investment is greater than 10%? In the answer that was given it says that the gain of the investment is X1+X2.  My question is why can we just group those together as one amount?  I was given a formula in my class that says the return on the investment would be the solution to the equation: -100+  X1/(1+r) +   X2/(1+r)2=0.  If this formula is used, a different solution would result for this problem.

How large a sample should be selected to provide a 95% confidence interval with a margin of error of 6? Assume that the population standard deviation is 20. Round your answer to next whole number.

There is a probability of 0.53 that there will be extremely cold weather this coming Winter. If it does, we expect investors of Star & Bucks to achieve a return of 0.15. Else, investors may expect a lower return of 0.07. Can you estimate the variance of this rate of return? (In Excel with Formulas) Please answer fast i give you upvote.

Consider a population proportion p = 0.20. a. What are the expected value and the standard error for the sampling distribution of the sample proportion with n = 20 and n = 58? Note: Round the standard error to 4 decimal places. Answer is complete and correct. n Expected value Standard error 20 58 0.20 0.20 0.0894 0.0525 b. Can you conclude that the sampling distribution of the sample proportion is approximately normally distributed for both sample sizes? Yes, the sampling distribution of the sample proportion is normally distributed for both sample sizes. No, the sampling distribution of the sample proportion is not normally distributed for either sample size. No, only the sample proportion with n = 20 will have a normal distribution. No, only the sample proportion with n = 58 will have a normal distribution. c. If the sampling distribution of the sample proportion is normally distributed with n = 20, then calculate the probability that the sample proportion is between 0.18 and 0.20.…

Maroon has an expected return of 20%, and a variance of 0.015. Gray has an expected return of 19%, and a variance of 0.005. The covariance between Maroon and Gray is 0.06. Using these data, calculate the variance of a portfolio consisting of 30% Maroon and 70% Gray.   0.008000 .004710 .033000 .029000 .17029

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