What would be the standard error in computing a confidence interval for the difference of proportions

Suppose a 90 percent confidence interval to estimate a population proportion was calculated from a sample proportion of 18 percent and a margin of error of 4 percent. What is the width of the confidence interval?

Suppose we know that a confidence interval for a population proportion is (0.105,0.355), with a sample proportion of p̂=0.23. What is the margin of error?

For a sample with a mean of 10, a std of 5 and an n of 30, what is the lower bound of the 95% confidence interval?

The accompanying data file contains 20 observations for t and yt.  Actual series are plotted along with the superimposed linear and exponential trends. Estimate the appropriate model to make a forecast for y21.  t      y       t      y           t         y            t        y 1   2.14   6    5.46     11    5.20       16    15.06 2   5.12   7    6.86     12     7.92      17    13.86 3   4.77   8    5.88     13    10.24     18    16.78 4   4.96   9    6.23     14    11.83     19    17.45 5   2.11   10   8.22    15    13.68     20    18.76

In a previous study, it was found that p hat=.73 for a particular sample. Suppose we would like to repeat this study. Give the sample size n, required to have the margin of error equal to .01, at the 98% confidence level.

The population standard deviation for the height of college football players is 2.7 inches. If we want to estimate a 95% confidence interval for the population mean height of these players with a 0.65 margin of error, how many randomly selected players must be surveyed

Imagine that you obtain a random sample of 125 M&M candies, and you notice that 28% of these candies are blue. If we convert the sample percentage of 0.28 to a sample proportion (by dividing 28 by 100), we get 0.28.

A 90% confidence interval for p=0.37 and n=475

Question 2: A random sample of 200 observations produced a sample proportion of 0.35. Determine the 98% confidence interval for the population proportion. rt Answer: