SOLUTION: There are 8 red, 5 blue and one yellow disc in a jar A. In jar B, there are 10 red, 9 blue and 2 white discs. A disc is drawn at random from each jar. Find the probability that

a)  both discs are white           

b)  both discs are red

c)  both discs are the same color

d)  both disks are different color


Before to start, notice that there are  (8 + 5 + 1) = 14 disks in jar A  and  

                                       (10 + 9 + 2) = 21 disks in jar B.


Now I answer questions a) - c):


a)  the probability is 0 (zero, ZERO), since there is no white disk in jar A;

b)  

c)   = , the sum of probabilities to have 2 red disks and/or 2 blue disks.