Men and muscle Ask young men to estimate their own degree of body muscle by choosing from a set of 100 photos. Then ask them to choose what they believe women prefer. The researchers know the actual degree of muscle, measured as kilograms per square meter of fat-free mass, for each of the photos. They can therefore measure the difference between what a subject thinks women prefer and the subject’s own self-image. Call this difference the “muscle gap.”

Here are summary statistics for the muscle gap from a random sample of 200 American and European young men: x– = 2.35 and sx =2.5.25

(a) Calculate and interpret a 95% confidence interval for the mean size of the muscle gap for the population of American and European young men.

(b) A graph of the sample data is strongly skewed to the right. Explain why this information does not invalidate the interval you calculated in part (a).