A researcher wants to determine if birthweights of children born to U. S. mothers is affected in any way when large megadoses of caffeine are consumed routinely by the mother during pregnancy. It is known that the birthweights are normally distributed with mean 7.5 pounds and standard deviation 1 pound. When drawing a sample of size 40 from such a population, and computing the mean birthweight in the sample, use the Central Limit Theorem to find the 2.5-th percentile of the distribution of sample means.