Dr. Ashby is studying the heart rate of adult men. Preliminary data suggests that the standard deviation of heart rates for adult men is σ = 7.5 σ=7.5sigma, equals, 7, point, 5 beats per minute (bpm). He plans on taking a sample of n nn men to construct a 99 % 99%99, percent confidence interval for the mean heart rate. He wants the margin of error to be no more than 3 bpm 3 bpm3, start text, space, b, p, m, end text.