Question 1163782
<br>
P(first box has a decoder ring) = 18/52<br>
P(second box has a decoder ring) = 17/51<br>
P(both have decoder rings) = (18/52)*(17/51) = (9/26)(1/3) = 3/26<br>
OR....<br>
Using a more sophisticated method -- which might be required in similar but more complicated problems....<br>
P(both have decoder rings) = (# of ways of choosing 2 of the 18 boxes with decoder rings) divided by (# of ways of choosing 2 of the 52 boxes)<br>
 = {{{C(18,2)/C(52,2) = ((18*17)/(2*1))/((52*51)/(2*1)) = (18*17)/(52*51) = (18/52)(17/51)}}}<br>
which is the same calculation as by the more elementary method.<br>