Researchers at a medical center studied the amount of caffeine, in milligrams (mg), contained in a 16-ounce cup of coffee made at one machine at the center’s cafeteria. They selected a random sample of 40 16-ounce cups of coffee made at different times of the day during a one-month period. The mean and standard deviation of the amount of caffeine in the sample were 159.88 mg and 36.72 mg, respectively. A graph of the sample data revealed a right skew with one outlier. The researchers will construct a confidence interval to estimate the amount of caffeine for all 16-ounce cups made at the machine. Which of the following conditions is not needed for the inference? A. The samples were selected at random. B. The observations are independent of one another. C. The sample size of 40 is less than 10% of the population size. D. The graph of the sample data is symmetric with no outliers. E. The sample size is large enough to assume that the sampling distribution of sample means is approximately normal.
Researchers at a medical center studied the amount of caffeine, in milligrams (mg), contained in a 16-ounce cup of coffee made at one machine at the center’s cafeteria. They selected a random sample of 40 16-ounce cups of coffee made at different times of the day during a one-month period. The mean and standard deviation of the amount of caffeine in the sample were 159.88 mg and 36.72 mg, respectively. A graph of the sample data revealed a right skew with one outlier. The researchers will construct a confidence
Which of the following conditions is not needed for the inference?
A. The samples were selected at random.
B. The observations are independent of one another.
C. The
D. The graph of the sample data is symmetric with no outliers.
E. The sample size is large enough to assume that the sampling distribution of sample means is approximately normal.
Given ;
Confidence interval =
=
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