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 aconfidence 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?АThe samples were selected at random.BThe observations are independent of one another.The sample size of 40 is less than 10% of the population size.DThe graph of the sample data is symmetric with no outliers.EThe sample size is large enough to assume that the sampling distribution of sample means is approximately normal