Total plasma volume is important in determining the required plasma component in blood replacement therapy for a person undergoing surgery. Plasma volume is influenced by the overall health and physical activity of an individual. Suppose that a random sample of 45 male firefighters are tested and that they have a plasma volume sample mean of x = 37.5 ml/kg (milliliters plasma per kilogram body weight). Assume that σ = 7.60 ml/kg for the distribution of blood plasma.

**(a) **Find a 99% confidence interval for the population mean blood plasma volume in male firefighters. What is the margin of error? **(Round your answers to two decimal places.)
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lower limit=

upper limit=

margin of error=

**B) ** Find the sample size necessary for a 99% confidence level with maximal margin of error E = 2.10 for the mean plasma volume in male firefighters. **(Round up to the nearest whole number.) **

_______ male firefighters