# statistics

Anonymous

Question description

1. Find the critical value za/2 that corresponds to the given confidence level.

2. Express the confidence interval 0.222 <p<0.888 in the form p^+E. P+E=_+_

3. A research institute poll asked respondents if they acted to annoy a bad driver. In the polln=2503 and x=1177 who said that they honked. Find the best point estimate of the population proportion p?

4. Use the given data to find the minimum sample size required to estimate a population proportion or percentage. Margin of error:0.08 confidence level 90% p and q unknown. n=?

5. 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 100 to 1800. Use technology and the estimated standard deviation to determine the sample size corresponding to a 99% confidence level and a margin of error of 100 points. What isn't quite right with this exercise? The range rule of thumb estimate for the standard deviation is?

6. Express the confidence interval (0.034,0.122) in the form of p-E<p<p+E.=_<p<_?

7. A clinical trial tests a method designed to increase the probability of conceiving a girl. In the study 620 babies were born, and 341 of them were girls. Use the sample data to construct a99% confidence interval estimate of the percentage of girls born. Based on theresult, does the method appear to be effective? _<p<_?

8. An online site presented thisquestion, "Would the recent norovirus outbreak deter you from taking a cruise?" Among the 34,575 people who responded 62% answered "yes." Use the sample data to construct a 90% confidence interval estimate for the proportion of the population of all people who would respond "yes" to that question. Does the confidence interval provide a good estimate of the population proportion? _<p<_?

9. In a poll of 546 human resourceprofessionals 43.0% said that body piercings and tattoos were big grooming red flagsAmong the 546 human resource professionals who were surveyed, how many of them said that body piercings and tattoos were big grooming red flags?

10. 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 theInternet? Assume that we want to be 99% confident that the sample percentage is within two percentage points of the true population percentage for all sales transactions. n=?

11. Use the given data to find the minimum sample size required to estimate a population proportion or percentage. Margin oferror: three percentage points; confidence level 95% from a prior study p is estimated by the decimal equivalent of 48% n=?

12. A researcher wishes to estimate the proportion of adults who have high-speed Internet access. What size sample should be obtained if she wishes the estimate to be within 0.05 with 95% confidence if: a: she uses a previous estimate of 0.58? b: she does not use any priorestimates?

13. The brand manager for a brand of toothpaste must plan a campaign designed to increase brand recognition. He wants to first determine the percentage of adults who have heard of the brand. How many adults must he survey in order to be 90% confident that his estimate is within fivefive percentage points of the true population percentage. Assume that nothing is known about the percentage of adults who have heard of the brand. n=?

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