given a jar contains four marbles, each a different color: red, blue, green, and yellow. If you draw two marbles from the jar, one after another, replacing the first before drawing the second,what is the probability of getting at least one red marble and one green marble?

Add up the probabilies of these results:

red followed by green
(1/4) x (1/4) = 1/16
red followed by red (same as above)
green folloed by red (same as above)
green followed by red (same as above)

(1/16) x 4 = ?