Exam 7: Confidence Intervals and Sample Size

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 If p^ is equal to 0.88, then q^ is equal to \text { If } \hat { p } \text { is equal to } 0.88 \text {, then } \hat { q } \text { is equal to } ________

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A chi-square variable cannot be negative, and the distributions are positively skewed.

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The prices (in dollars) for a graphing calculator are shown below for 8 online vendors. Estimate the true mean price for this particular calculator with 95% confidence. 121 125 151 129 127 133 121 125

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Jennifer wants to find a 95% confidence interval for the time it takes her to get to work. She kept records for 30 days and found her average time to commute to work was 20.5 minutes with a standard deviation for the population of 3.9 minutes. Jennifer's margin of error would be 1.4 minutes.

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In order to find confidence intervals for variances and standard deviations, one must assume that the variable is .

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A random sample of 50 voters found that 46% were going to vote for a certain candidate. Find the 95% limit for the population proportion of voters who will vote for that Candidate.

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The confidence level of an interval estimate of a parameter is the probability that the interval estimate will contain the parameter.

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The Pizza Shop wanted to determine what proportion of its customers ordered only cheese pizza. Out of 80 customers surveyed, 15 ordered only cheese pizza. What is the 99% confidence interval of the true proportion of customers who order only cheese Pizza?

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Measurements were made of the milk fat content (in percent) in six brands of feta cheese variety of goat cheese), with the following results. Assume that the population is normally distributed. 27.5 19.3 32.0 23.5 24.6 16.9 Construct a 90%90 \% confidence interval for the population standard deviation σ\sigma .

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A population has a standard deviation σ=19.8\sigma = 19.8 . How large a sample must be drawn so that a 99%99 \% confidence interval for μ\mu will have a margin of error equal to 4.7?4.7 ?

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Find the 95% confidence interval for the standard deviation of the lengths of pipes if a sample of 11 pipes has a standard deviation of 10.6 inches.

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The rounding rule for a confidence interval for a proportion is to round off to three decimal places.

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Find the critical value tα/2t _ { \alpha / 2 } needed to construct a confidence interval of the given level with the given sample size. Level 95%95 \% , sample size 11

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A study of elephants is conducted to determine the average weight of a certain subspecies of elephants. The standard deviation for the population is 500 pounds. At a 90% level, how many elephants need to be weighed so the average weight will be Accurate to within 250 pounds?

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 Find the critical value zα/2 needed to construct a(n) 99.5% confidence interval. \text { Find the critical value } z _ { \alpha / 2 } \text { needed to construct a(n) } 99.5 \% \text { confidence interval. }

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The value for χrigh 2\chi _ { \text {righ } } ^ { 2 } 2 right for a 95%95 \% confidence interval when n=15n = 15 is 26.11926.119 .

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Find the level of the confidence interval that has the given critical value. 2.16

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What is the value for χ2\chi ^ { 2 } for a 95%95 \% confidence interval when n=18n = 18 ?

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Find the margin of error for the given confidence level and values of xx and nn . x=111,n=194x = 111 , n = 194 , confidence level 99%99 \%

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In a sample of 45 mice, a biologist found that 40% were able to run a maze in 30 seconds or less. Find the 95% limit for the population proportion of mice who can run a maze in 30 seconds or less.

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