The salaries of professional baseball players are heavily skewed right with a mean of $3.2 million and a standard deviation of $2 million. The salaries of professional football players are also heavily skewed right with a mean of
$1.9 million and a standard deviation of $1.5 million. A random sample of 40 baseball players' salaries and 35
football players' salaries is selected. The mean salary is determined for both samples. Let 7-7, represent the
difference in the mean salaries for baseball and football players. Which of the following represents the standard
deviation of the sampling distribution for 5-7,?