Two bags contain different numbers of red and blue marbles. A marble is removed from one of the bags. The marble is blue. What is the probability that it was removed from bag A?
You and I play a game involving successive throws of a fair coin.
Suppose I pick HH and you pick TH. The coin is thrown repeatedly
until we see either two heads in a row (I win) or a tail followed
by a head (you win). What is the probability that you win?
CD Collection
Age 14 to 16 Short Challenge Level
I have 3 Elvis Presley CDs, 2 Beatles CDs and 1 Queen CD.
How many different ways can they be lined up on a shelf if I must keep all the CDs by the same artist together?