4 out of 52 which reduce down to 1/13
The probability of picking one red card of a deck of 52 playing cards is 26 out of 52, or 1 out of 2.
The probability of picking a diamond out of a standard deck of 52 cards is 13 in 52, or 1 in 4, or 0.25.
3 out of 13
12/52nd
The probability that a single card, drawn at random, is a 9 is 1/13.
If it is an ordinary pack of playing cards then the probability is 0.5
1/52
It is 3/13.
In a normal deck of cards, it is 1.
It is 1/4.
To determine the probability of picking 3 cards of one suit and 1 card of another in a standard 52 card deck, consider each card one at a time. The probability of picking a card in any suit is 52 in 52, or 1. Since there are now only 12 cards in the first suit, the probability of picking a card in the same suit is 12 in 51, or 4 in 17, or 0.2353. Since there are now only 11 cards in the first suit, the probability of picking a card in the same suit is 11 in 50, or 0.22. Since there are still 39 cards in the remaining three suits, the probability of picking a card in a suit different than the first is 39 in 49, or 0.7959. The probability of picking 3 cards of one suit and 1 card of another in a standard 52 card deck is, therefore, the product of the probabilities of each card, or (52 in 52) (12 in 51) (11 in 50) (39 in 49), or 267696 in 6497400, or 0.0412, or about 1 in 25.
The answer depends on how many cards are picked, whether they are picked at random, from what sort of pack, and whether or not cards are replaced before the next one is picked. The probability that a single card, picked at random from a regular 52 card deck is red, is 0.5