In the article “Ultrasound evaluation of the costophrenic recess as a marker of phrenic nerve function” published in The Internet Journal of Anesthesiology (Martin, 2018), the authors reported that in a pilot study the mean body mass index (BMI) of the

???? = 20 individuals in their study was ????̄ = 30.8 kg m2 with a sample standard deviation of ???? = 6.8. Use this information to compute a 95% confidence interval for the mean BMI assuming the distribution of BMI is approximately normal.