Suppose that you randomly draw 20 cards from a standard deck of 52 cards with replacement. What is the probability of drawing at least 7 hearts?
tediously long question ....
you DON'T want
0 hearts, 1 heart, 2 hearts,... 6 hearts
prob(your problem)
= 1 - ( C(13,0)*C(39,20) + C(13,1)*C(39,19) + ... + C(13,6)*C(39,24) )/C(52,20)
= ...
you do the button pushing