21) If two random variables are independent,thena. knowing the value that one takes on tells nothing about the value the other will take on.b. the correlation coefficient between the two variables...

21) If two random variables are independent,then a. knowing the value that one takes on tells nothing about the value the other will take on. b. the correlation coefficient between the two variables will be zero. c. the covariance between the two variables will be zero. d. a and b