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  #1  
Old 12-15-2007, 11:31 AM
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Trick Math Question?

A dog has five puppies. What are the odds that all of them are female?

a) 1/32

b) 1/6?

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  #2  
Old 12-15-2007, 11:34 AM
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Where's the trick?
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  #3  
Old 12-15-2007, 11:34 AM
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hmm.. well if you divide 5 by the number of parsecs per square inch of the mothers nose multiplied by cosine theta to the negative 13th power you will be given a value X

then take X and figure it in with the amount of fleas per new born puppy to square kilometers in the state of ohio

Its as easy as non euclidean geometry on mars during a wind storm
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Old 12-15-2007, 11:39 AM
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Quote:
Originally Posted by Matt L View Post
Where's the trick?
I don't know the answer but it seems like a trick to me. It could be both but try and explain it to me though when you're done giving me the answer.
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Old 12-15-2007, 11:39 AM
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Quote:
Originally Posted by TheDon View Post
hmm.. well if you divide 5 by the number of parsecs per square inch of the mothers nose multiplied by cosine theta to the negative 13th power you will be given a value X

then take X and figure it in with the amount of fleas per new born puppy to square kilometers in the state of ohio

Its as easy as non euclidean geometry on mars during a wind storm
I hope gravity gets you.
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Old 12-15-2007, 11:43 AM
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Isn't it 1/32? To get the odds of a series of independent events occurring together, you multiply the odds of each one by the others??
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  #7  
Old 12-15-2007, 11:52 AM
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Strictly speaking, they aren't independent events. That is, one male puppy means one less male sperm in the mix for the rest.

However, the difference is very small here. I'm sure that the odds of having a female puppy aren't exactly 1/2 anyway, but answer (a) is a whole lot closer to the true value than (b).
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Old 12-15-2007, 11:53 AM
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Quote:
Originally Posted by Kuan View Post
A dog has five puppies. What are the odds that all of them are female?

a) 1/32

b) 1/6?
Kerry is correct.

1 in 32.

It’s a factorial thing.

There’s a 1 in two chance any will be female, so start with the number 2 and do the math:

2x1=2 for the 1 in 2 chance the first one is a female.
Then for the rest of the puppies:
2x2=4 (1 in 4 the second one is a female too)
Then continue:
4x2=8 (for the 3rd puppy being female too)
and so forth for all 5 puppies:
8x2=16 (for the 4th)
and:
16x2=32 (for the 5th)

Thus, 1 in 32 chance of all five being females.

No trick to that.


(Unless I'm totally wrong, in which case, I'm glad I don't own the dog. And you're glad I don't teach math.)
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Old 12-15-2007, 11:56 AM
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You're correct except for the use of the term "factorial." You're thinking of combinatorics, which isn't part of this problem.
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Old 12-15-2007, 12:03 PM
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Originally Posted by Matt L View Post
You're correct except for the use of the term "factorial." You're thinking of combinatorics, which isn't part of this problem.
Actually its is part of the same type of math solutions. I was going to add:

That works if the items can be the same as any other, or are the same. (i.e. all female puppies)

Now, if you want the odds (or number of combinations)of 5 items coming up different than the rest in any non-identical sequence:

It’s:
5x4x3x2x1 or 120 for 120 different combinations of 5 items. Thus, you’d have about a 1 in 120 chance of picking 5 different items out of a hat in the same order twice.

I didn't want to use the term “factoral statistical analysis”, as words that most spell checkers would flag start popping up if he were to go looking. Sorry.
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Old 12-15-2007, 12:08 PM
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Quote:
Originally Posted by Matt L View Post
Strictly speaking, they aren't independent events. That is, one male puppy means one less male sperm in the mix for the rest.

However, the difference is very small here. I'm sure that the odds of having a female puppy aren't exactly 1/2 anyway, but answer (a) is a whole lot closer to the true value than (b).
Correct.

Hey Kuan - Did they give you an X/Y report on both the male and female breeding dogs ?
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Old 12-15-2007, 12:43 PM
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Quote:
Originally Posted by WVOtoGO View Post
Correct.

Hey Kuan - Did they give you an X/Y report on both the male and female breeding dogs ?
Assuming the odds are exactly 1/2 and 1/2.

I was thinking there are only six combinations.

M F
5 0
4 1
3 2
2 3
1 4
5 0

Hence the odds are 1/6?
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  #13  
Old 12-15-2007, 12:53 PM
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Related:

What are the differences in the odds of a person with no knowledge, randomly choosing answers, getting a 100% on these two tests:

A 10 question multiple choice test with 4 possible answers on each question.

A 10 question matching test with 10 answers each of which is only a correct answer for one of the questions.
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  #14  
Old 12-15-2007, 12:56 PM
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Quote:
Originally Posted by TheDon View Post
hmm.. well if you divide 5 by the number of parsecs per square inch of the mothers nose multiplied by cosine theta to the negative 13th power you will be given a value X

then take X and figure it in with the amount of fleas per new born puppy to square kilometers in the state of ohio

Its as easy as non euclidean geometry on mars during a wind storm
Yes it's really easy, anyone with an I.Q. of 200 can do it..
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  #15  
Old 12-15-2007, 01:27 PM
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Quote:
Originally Posted by kerry View Post
Related:

What are the differences in the odds of a person with no knowledge, randomly choosing answers, getting a 100% on these two tests:

A 10 question multiple choice test with 4 possible answers on each question.

A 10 question matching test with 10 answers each of which is only a correct answer for one of the questions.
Exactly 1 in 1,048,576

2.75573192×10^-7 or about 1 in 36 million

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