show how u got ur ans.
2007-04-12 09:09:04 · 10 answers · asked by alona p 1 in Science & Mathematics ➔ Mathematics
[EDIT: I realized I made a big mistake when I first posted this, but I came back to correct it.]
I get 175 / 221 (I'll explain how in a moment). I know that's a different answer from what others are getting.
I see some people are giving 7/13 for the answer. That's the probability of drawing ONE card. Others are accidentally counting the red-suited king cards twice in their calculations (remember "drawing a red card" and "drawing a king" are not independent events!). Also, some people are (like I initially did) misreading the problem as "the probability of getting a king or a red for BOTH cards". But the question is really "If you draw 2 cards, what's the probability that AT LEAST ONE is a red or king?"
I think the simplest way to do this is to find the probability of drawing two cards that are NEITHER red nor kings, and taking that probability's difference from 1.
There are 26 black cards, 2 of which are kings, which leaves 24 of 52 "wrong" cards. The probability of drawing one of these is 24/52, which leaves 23 "wrong" cards left in a deck of 51. So drawing a second one is 23/51. So the probability is:
1 - (24/52)(23/51) = 1 - 552/2652 = 2100 / 2652 = 525 / 663 = 175 / 221
I see some others got the same answer by working it out as P(getting the right card the first time) + P(getting a right card the second time) - P(getting a right card both times), or somthing similar.
2007-04-12 09:15:57 · answer #1 · answered by Anonymous · 2⤊ 2⤋
There are 4 kings in the deck, and 26 red cards (hearts and diamonds). 2 of the kings are red, so 26 + 4 - 2 = 28 cards are kings or red cards.
The probability for the first card to be one is 28/52.
If it is not, and the probability for this is 24/52, the probability to select a king or a red card is 28/51.
The overall probability is 28/52 + 24/52 * 28/51 =
= 7/13 + 6/13 * 28/51 = 7/13 + 168/663 = (357 + 168)/663 =
= 525/663 = 175/221
2007-04-12 09:23:17 · answer #2 · answered by Amit Y 5 · 2⤊ 1⤋
There are 52 cards in a deck. The probabilty of drawing a King is 4/52 or 1/13. Since you are looking to find out the probability that a king or a red card is drawn, there are 26 red cards and 2 black kings. (Note the 2 red kings are included in the 26 red cards.)
So (26+2)/52=28/52=7/13
If you want a percentage, just divide 7 by 13......53.85%
2007-04-12 09:18:11 · answer #3 · answered by Michelle M 2 · 1⤊ 2⤋
King possibility = 4/fifty two (a million/13) b/c there are 4 kings in deck of fifty two playing cards crimson Card possibility = 26/fifty two (a million/2) b/c there are 26 crimson playing cards King or crimson Card possibility = 28/fifty two (7/13) b/c there are 26 crimson playing cards and a pair of kings that at the instant are not crimson (26+2 = 28) desire i become of help!
2016-10-02 21:27:15 · answer #4 · answered by ? 4 · 0⤊ 0⤋
P(king OR red) = P(king) + P(red) - P(king AND red)
we must find the probability of getting one or the other, and then subtract the probability that the card is a red king, so that we don't count these cards twice. we also know that there are 52 total cards in the deck.
P(king) = 4/52 (there are 4 kings:club, spade, heart, diamond)
P(red) = 26/52 (13 each of diamonds and hearts)
P(king AND red) = 2/52 (king of diamond and king of hearts)
therefore:
P(king OR red) = 4/52 + 26/52 - 2/52 = 28/52 = 7/13
2007-04-12 09:30:48 · answer #5 · answered by math_whiz 2 · 1⤊ 2⤋
there are 52 cards in a deck. Half are red, so the probability of drawing a red card is 1:2. to draw two red cards is (1/2)x(1/2)=1/4 or 25%
there are four kings in a deck, so the probability of drawaing one king is 4:52 or 1:13. the probability of drawing two kings is (1/13)x(1/13)=1/169
2007-04-12 09:17:00 · answer #6 · answered by Tim K 2 · 1⤊ 3⤋
there are 26 red cards, and there are another 2 kings not including the red king, so during the first drawing u got 28/52 chances. then on the second draw, u have 28/51 chances so if u draw a red on the first try then u dont need to know the outcome to second, but if u didnt draw a red on first try then u need a red on second... so thats (black on first try)x(red on second try) so thats 24/52x28/51=672/2652 then u add the chance of u getting a red on the first try, or 28/52 which comes out to be 2100/2652 or 175/221 or 79.1%
2007-04-12 09:16:30 · answer #7 · answered by Zack C 3 · 2⤊ 1⤋
4 kings and 26 red cards so 7/13
2007-04-12 09:37:35 · answer #8 · answered by Anonymous · 0⤊ 2⤋
28/52 or 7/13
there are 4 kings and 26 red cards.
since 2 red cards are alredy kings you put 24 cards
add them and put them over the total number of cards.
2007-04-12 09:12:34 · answer #9 · answered by Joemaroon 2 · 0⤊ 2⤋
is it 30/52
2007-04-12 09:15:28 · answer #10 · answered by melissa 2 · 0⤊ 3⤋