Constructing Confidence Intervals
In a clinical trial of a new drug, 23 subjects experience headaches among the 216 subjects treated with the new drug. Construct a 99% confidence interval estimate for the proportion of treated subjects who experience headaches.
Margin of Error:
Confidence Interval:
Interpretation:
In a survey of 3106 adults aged 57 through 85 years, it was found that 80.4% of them used at least one prescription medication. Construct a 90% confidence interval estimate of adults aged 57 through 85 who use at least one prescription medication.
Margin of Error:
Confidence Interval:
Interpretation:
In a program designed to help patients stop smoking, 202 patients were given sustained care, and 83.2% of them were no longer smoking after one month. Among 207 patients given standard care, 63.8% were no longer smoking after one month. Using a 95% confidence level, construct two confidence interval estimates of the percentages of success.
Margin of Error:
Confidence Interval:
Interpretation:
Margin of Error:
Confidence Interval:
Interpretation:
Construct a 90% confidence interval for randomly selected weights of newborn girls:
n = 282, = 32.9 hg, s = 7.8 hg.
Margin of Error:
Confidence Interval:
Interpretation:
A data set includes 108 body temperatures of healthy adult humans having a mean of 98.2°F and a standard deviation of 0.64°F. Construct a 99% confidence interval estimate of the mean body temperature of all healthy humans.
Margin of Error:
Confidence Interval:
Interpretation:
Construct two confidence interval estimates for the mean pulse rate of adult females and adult males. Use a 90% confidence level.
Males
Females
n =
40
40
=
67.2
75.7
s =
12.27
13.41
Margin of Error:
Confidence Interval:
Interpretation:
Margin of Error:
Confidence Interval:
Interpretation:
A simple random sample from a population with normal distribution of 100 body temperatures has = 98.3°F and s = 0.64°F. Construct a 95% confidence interval estimate of the standard deviation of body temperature of all healthy humans.
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=
Confidence Interval:
Interpretation:
Construct a 95% confidence interval estimate of the standard deviation of weights for birthday candles. Assume that the sample is a simple random sample obtained from a population with a normal distribution. Use the following statistics: n = 15, = 1.71, and
s = 0.23.
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Confidence Interval:
Interpretation:
A clinical trial was conducted to test the effectiveness of a drug treating insomnia in older subjects. After the treatment with the drug, 28 subjects had a mean wake time of 97.9 minutes with a standard deviation of 41.2 minutes. Assume that the 28 sample values appear to be from a normally distributed population and construct a 95% confidence interval estimate of the standard deviation of wake times for a population with drug treatments.
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Confidence Interval:
Interpretation:
Created for Spring 2021
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