A jar contains m+nchips, numbered 1,2,,n+m. A set of size nis drawn. If we let X denote the number of chips drawn having numbers that exceed each of the numbers of those remaining, compute the probability mass function of X.

Short Answer

Expert verified

P(X=k)=n+m-k-1n-kn+mn

Step by step solution

01

Given information

A jar contains m+nchips, numbered 1,2,,n+m. A set of size n is drawn.

02

Explanation

Observe that X{0,,n}. Take any k{0,,n}. Let's calculate P(X=k). Observe that there are n+mnof all possible combinations of taken chips. If X=k, that means that we have taken klargest number, have not taken (k+1)stlargest number and all other remaining n-knumbers out of remaining n+m-k-1 numbers have been taken freely.

03

Final answer

The probability mass function is

P(X=k)=n+m-k-1n-kn+mn

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