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probability math question
- Thread starter ATLATLATL
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Isn't it just (26/52)*(25/51)*(24/50)? There are 26 black cards to start, but each time you pick another there is one less black card and also one less total card.
Yes.
ok guys, here is an exact problem for you but destroyer tries to be unique and solve it differently!!!, and i don't see why on earth should you solve the following problem differently than the one ATLATLA posted
there are 3red, 4white, 5blue balls in a jar. What is the probability of drawing a red, a white, a blue without replacement?
shouldn't it be like this:
(3/12)(4/11)(5/10)=1/22 ????????
pleeeez let me know, I desperatly need help w/that one
there are 3red, 4white, 5blue balls in a jar. What is the probability of drawing a red, a white, a blue without replacement?
shouldn't it be like this:
(3/12)(4/11)(5/10)=1/22 ????????
pleeeez let me know, I desperatly need help w/that one
dentalkity I would of solved it the same way you just did, some of these problems you have to do the math, no short way of doing it......you should probably try to reduce the fractions as much as you can before doing the final multiplication....just my grain of sand....danbarr
Correct, unless you can choose them in any order in which case I think it would be 3/11.
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Is that because you can arrange the 3 colors in 3!=6 ways? Would that work for any probability problem if order didn't matter?
ok i get it streetwolf, but how can i tell if it's in order or not?, i think in one of your posts you said one should not consider order unless it clearly indicates that order matters, and the wording of this prob. is very ambiguous, even Ex_EE couldn't tell if its in order or not, I couldn't tell either, and of course the answer choices provide both answers, 1/22 and 3/11, they say correct answer is 3/11,
this type of problems is one of the easiest and i don't want to miss it just because i can't tell if it's in order or not, so is there any criteria to find out...any probability experts???
this type of problems is one of the easiest and i don't want to miss it just because i can't tell if it's in order or not, so is there any criteria to find out...any probability experts???
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The only thing I can think of is that when you see "probablility" you have to include all available options in the total regardless of whether some of them look the same. Each possibility is a unique option. So with probablility order should matter every time. Only with "how many ways can you pick" type problems would you have to determine whether order matters to use combination or permutation. Probability questions are like reverse permutations, right?
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Well this just asked about drawing the 3 colors. It never actually said, 'in that order'. So I suppose in this case, order mattered. It was pretty poorly worded though.
This one has been posted before.
The first person can sit in any seat. Once they choose their seat (it doesn't matter which one they choose), we then consider any other seat. There are 5 people left who can sit there. Then we consider another seat. There are 4 people left who can sit there. etc etc. So the answer is 5! = 120.
The answer is NOT 6! = 720 because it wants to know how many ways they can sit around a table. If you don't want the order to be A B C D E F then it doesn't make sense to consider arrangements where that's the order but everyone is shifted over one, two, etc seats.
Another way to think about it is 6! / 6. The first seat can go to any of the 6 people, the next seat goes to any of the remaining 5, etc. But then since any given order will occur 6 times each (due to everyone shifting the same # of seats over in the same direction), you divide your answer by 6.
This has also been posted before. There are (9 choose 6) = 84 ways to pick the 6 coins that will land as tails. Then, for each of those coins to land as tails, you multiply by (1/2). So that's (1/2)^6. Finally, you multiply by (1/2) for each of the remaining coins to land as heads. So that's another (1/2)^3. In total you have 84 * (1/2)^6 * (1/2)^3 = 84 * (1/2)^9 = 84/512 = 42/256 = 21/128 = 0.1640625.
