The Singing Hedgehog Guide to:
Probability 2 - Cards
With 4 suits each of 13 cards we generally get quarters and thirteenths. Here are some probabilities relating to cards:
Chance of getting a red card
26/52 = 1/2
Chance of getting a spade
13/52 = 1/4
Chance of getting a picture card (J,Q,K,A)
12/52 = 4/13
Chance of getting a four
4/52 = 1/13
Chance of getting a red 7
2/52 = 1/26
Chance of getting a 5 of clubs
1/52
These all change of course if a card is not replaced. Chances are then out of 51; useful to remember that 51 is 3 x 17 so some cancelling may be possible