Question

A research institute poll asked respondents if they felt vulnerable to identity theft. In the​ poll, n=1081 and x=598 who said​ "yes." Use a 90 % confidence level.

- Find the best point estimate of the population proportion p.

A research institute poll asked respondents if they acted to annoy a bad driver. In the​ poll, n =2563, and x=1061 who said that they honked. Use a 99% confidence level.

- Find the best point estimate of the population proportion p

A study of 420,052 cell phone users found that 138 of them developed cancer of the brain or nervous system. Prior to this study of cell phone​ use, the rate of such cancer was found to be 0.0342​% for those not using cell phones.

- A study of Use the sample data to construct a 90% confidence interval estimate of the percentage of cell phone users who develop cancer of the brain or nervous system

__% <p<__%

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 seven percentage points of the true population percentage for all sales transactions.

- n=

An engineer is going to redesign an ejection seat for an airplane. The seat was designed for pilots weighing between 140 lb and 191lb. The new population of pilots has normally distributed weights with a mean of 148 lb and a standard deviation of 33.7 lb.

- If a pilot is randomly​ selected, find the probability that his weight is between 140 lb and 191 lb. the probability is ______

Answer 1

Here n=1081 and x=598

So

For 90% CI z value is 1.645 as P(-1.645<z<1.645)=0.90

So Margin of Error is

Hence CI is