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WorksheetsLength of Confidence Interval and Sample Size
Total questions: 10
Worksheet time: 14mins
A population has a standard deviation of σ = 17.3. How large of a sample must be drawn so that a 95% confidence interval for µ will have a Margin of Error equal to 1.4?
586.6
587
586
585
We plan to survey college seniors to see what proportion plan to attend grad school next year. Using 98% confidence, how many students should we survey if we wish the margin of error to be within 3%?
approximately 1170
approximately 1500
approximately 1050
approximately 40
We wish to obtain a 95% confidence interval for the average SAT score for Midlo students. The standard deviation of all SAT scores is 180. We should sample (a) students if we wish the margin of error to be within 40 points. ROUND ANSWER TO THE NEAREST TEN (for example, 20, 120, etc.)
A research group wishes to estimate the mean amount of time (in hours) that members of a fitness center spend exercising each week. They want to estimate the mean within a margin of error of 0.5 hours with a 95% level of confidence. Previous data suggests that the standard deviation of the population is 2.2. Which of the following is the smallest sample size they could use?
60
75
90
180
True or False: The more confident you want to be, the smaller your confidence interval will be.
True
False
Which of the following changes to a study would result in a smaller confidence interval?
increasing the confidence level, increasing the sample size
increasing the confidence level, decreasing the sample size
decreasing the confidence level, decreasing the sample size
decreasing the confidence level, increasing the sample size.
A research company wants to estimate the proportion of people who like oatmeal. They want the confidence level to be 95%. The company gets 325 people to sign up for the survey, but on the day that the survey is issued, only 250 people show up and take the survey. What happens to the confidence interval?
It stays the same
It gets smaller
It gets larger
Not enough information
