Question

Many young men in North America and Europe (but not in Asia) tend to think they need more muscle to be attractive. One study presented 200 young American men with 100 images of men with various levels of muscle. Researchers measure level of muscle in kilograms per square meter (kg/m2) of fat-free body mass. Typical young men have about 20 kg/m2. Each subject chose two images, one that represented his own level of body muscle and one that he thought represented "what women prefer." The mean gap between self-image and "what women prefer" was 2.35 kg/m2 Suppose that the "muscle gap" in the population of all young men has a Normal distribution with standard deviation 2.5 kg/m2. Give a 90% confidence interval for the mean amount of muscle young men think they should add to be attractive to women. (Enter your answers rounded to four decimal places.) lower limit- kg/m2 upper limit- kg/m2

Answer 1

The statistical software output for this problem is:

One sample Z summary confidence interval μ : Mean of population Standard deviation = 2.5 90% confidence interval results Mean n Sample Mean Std. Err. L. Limit U. Limit 200 2.35 0,1767767 2.0592282 2.6407718

Hence,

Lower limit = 2.0592

Upper limit = 2.6408