/sci/ - Science & Math » Thread #7624810

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Buddha Thu 29 Oct 2015 20:10:36 No.7624810 View Reply Report Delete

A box contains 10 tickets with the numbers {1,1,1,2,2,2,2,3,3,4}

If tickets are drawn successively with replacement, what is the probability that the first 2 appears before the first 3?

Anonymous

Anonymous Thu 29 Oct 2015 20:12:41 No.7624814 Report Delete

Quoted By: >>7624824

homework threads belong to >>>/hm/

Anonymous

Anonymous Thu 29 Oct 2015 20:13:48 No.7624817 Report Delete

Quoted By: >>7624833

This is a tough 1, ignore the 3 aspect of the question the answer is (4/10) / ( 1 - (4/10) )
or infinite series of (4/10)^k

Anonymous

Anonymous Thu 29 Oct 2015 20:15:21 No.7624824 Report Delete

Quoted By:

>>7624814
Go fuck yourself this is a stats thread

Anonymous

Anonymous Thu 29 Oct 2015 20:16:50 No.7624833 Report Delete

Quoted By:

>>7624817
Your answer is right but the first factor is representative of the non 2 and 3s so 4/10 ^ k -1 multiplied by 4/10 for the kth term being a 2 which just happens to be 4/10 ^ k or series of it at least

Buddha

Buddha Thu 29 Oct 2015 20:19:47 No.7624841 Report Delete

Quoted By: >>7624854

>>7624810
OP here lets try another!

same box

If tickets are drawn successively with replacement, what is the probability that it takes atleast 5 draws to see the second 4?

Anonymous

Anonymous Thu 29 Oct 2015 20:24:48 No.7624854 Report Delete

Quoted By:

>>7624841
ok so we want to see the 2nd 4 on the 5th draw

so the 1st 4 draws we want 1 4

lets use 1 subtracted from a summation from 2 to 4 of a negative binomial dist (x-1Choose1)(4/10)^2(6/10)^x-2

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