Question

Find the sample size, n, needed to estimate the percentage of adults who have consulted fortune tellers. Use a 0.04 margin of error, use a confidence level of 98% and use results from a prior poll suggesting that 11% of adults have consulted fortune tellers.

A student wants to estimate the mean score of all college students for a particular exam. First use the range rule of thumb to make a rough estimate of the standard deviation of those scores. Possible scores range from 800 to 2200 Use the TI-83/84 and the estimated standard deviation to determine the sample size corresponding to a 95​% confidence level and a margin of error of 100 points.

A programmer plans to develop a new software system. In planning for the operating system that he will​ use, he needs to estimate the percentage of computers that use a new operating system. How many computers must be surveyed in order to be 95% confident that his estimate is in error by no more than four percentage points question marks? Assume that nothing is known about the percentage of computers with new operating systems.

Many states are carefully considering steps that would help them collect sales taxes on items purchased through the Internet. How many randomly selected sales transactions must be surveyed to determine the percentage that transpired over the Internet? Assume that we want to be 95% confident that the sample percentage is within eight percentage points of the true population percentage for all sales transactions.

Many states are carefully considering steps that would help them collect sales taxes on items purchased through the Internet. How many randomly selected sales transactions must be surveyed to determine the percentage that transpired over the Internet? Assume that we want to be 90% confident that the sample percentage is within two percentage points of the true population percentage for all sales transactions.

Find the sample​ size, n, needed to estimate the percentage of adults who have consulted fortune tellers. Use a 0.08 margin of​ error, use a confidence level of 90​% and use results from a prior poll suggesting that 11​% of adults have consulted fortune tellers.

Answer 1

We would be looking at the first question here:

Find the sample size, n, needed to estimate the percentage of adults who have consulted fortune tellers. Use a 0.04 margin of error, use a confidence level of 98% and use results from a prior poll suggesting that 11% of adults have consulted fortune tellers.

From standard normal tables, we have:
P(Z < 2.326) = 0.99, therefore due to symmetry, we get here:

P( -2.326 < Z < 2.326) = 0.98

The margin of error is computed here as:

Therefore the sample size is computed here as:

Therefore 332 is the sample size required here.