Suppose that a researcher is interested in estimating the mean systolic blood pressure, , of executives of major corporations. he plans to use the blood pressures of a random sample of executives of major corporations to estimate . assuming that the standard deviation of the population of systolic blood pressures of executives of major corporations is mm hg, what is the minimum sample size needed for the researcher to be confident that his estimate is within mm hg of ?

1- is the product of two rational numbers irrational or rational? first, make a hypothesis by multiplying two rational numbers. then, use variables such as x=a/b and y=c/d and the closure property of integers to prove your hypothesis. 2- what do you think the product of a nonzero rational number and an irrational number is? is it rational or irrational? make use of variables, the closure property of integers, and possibly a proof by contradiction to prove your hypothesis. 3- why do we have to specify that the rational number must be nonzero when we determine what the product of a nonzero rational number and an irrational number is? if the rational number were 0, would it give us the same result we found in part b?