In a school population, assume that the probability of being white equals .40; black equals .30; Hispanic equals .20; and Asian- American equals .10. What is the probability of
(a) A student being either white or black.
(b) A student being neither white nor black.
(c) Pairs of black and white students being selected together, assuming ethnic background has no role.
(d) Given that a black student has been selected, that his/ her companion is white, assuming ethnic background has no role.
(e) Given that a black student has been selected, that his/ her companion is white, assuming students tend to congregate with companions with similar ethnic backgrounds. In this case, would the probability of the companion being white be less than .40, equal to .40, or more than .4040?