The Magic Cafe Forum Index » » Magical equations » » Help. Am I making this too simple? (0 Likes)

 El_Lamo Special user Canada 589 Posts Posted: Feb 10, 2004 07:17 pm    0 I have eight cards, six black and two red. If the spectator randomly selects the cards, face down, one at a time... what are the odds that the last card will be red? Is it 25% Cheers - El Lamo Life is a system of circumstance presented coincidently in an illusory way. Hideo Kato Inner circle Tokyo 5649 Posts Posted: Feb 10, 2004 09:17 pm    0 Although I don't know why you need this probability, the solution is simple. It is same as the probability in which a red card is selected as the first one. So you are right. Hideo Kato rgranville Elite user Boston area 462 Posts Posted: Feb 11, 2004 06:52 am    0 And since nobody asked, I'll give you the mathematical breakdown. In general, the number of different ways you can arrange 8 cards is 8!. Since 6 of your cards are black, we have to divide that number by 6! And since 2 of the cards are red, we have to divide again by 2! That leaves us with 28 different ways to arrange a packet of 6 black cards and 2 red cards. Now how many of these arrangements have a red card as the last? Well, with the last card as red, that means we have to arrange the other 7. There are 7! ways to arrange 7 cards, and since 6 of them are black, we have to divide this by 6!. That leaves us with 7 ways to have the last card as red. Thus the odds are 7 out of 28, or 1 out of 4, or 25%. :cucumber: LobowolfXXX Inner circle La Famiglia 1192 Posts Posted: Feb 11, 2004 12:20 pm    0 Quote:On 2004-02-11 07:52, rgranville wrote: And since nobody asked, I'll give you the mathematical breakdown. It's good practice. Way to go! "Torture doesn't work" lol Guess they forgot to tell Bill Buckley. "...as we reason and love, we are able to hope. And hope enables us to resist those things that would enslave us." Necromance New user Pattingham, UK 53 Posts Posted: Mar 2, 2004 01:22 pm    0 Quote:On 2004-02-11 07:52, rgranville wrote: And since nobody asked, I'll give you the mathematical breakdown. Well done! I'm not a great fan of mathematics but that was certainly invigorating Any sufficiently advanced technology is indistinguishable from magic-Arthur C. Clarke Any technology distinguishable from magic is insufficiently advanced-probably NOT Arthur C. Clarke Heinz Weber New user Austria 83 Posts Posted: Mar 16, 2005 12:23 pm    0 There is always a way to do it more sophisticated! Heinz The Magic Cafe Forum Index » » Magical equations » » Help. Am I making this too simple? (0 Likes)
 [ Top of Page ]