An urn holds 4 red, 3 blue, and 2 green marbles. Three marbles are selected, altogether, without replacement. Let Y be the number of red marbles obtained. What is the expectation of Y?
An urn holds 4 red, 3 blue, and 2 green marbles.
Three marbles are selected, altogether, without replacement.
Let Y be the number of red marbles obtained.
What is the expectation of Y?
The number of marbles in the urn is given as follows:
The variable
In this case, each obtained marble has the only option of "being red" (defined as success) or "not being red" (defined as failure). As a finite marbles are selected (i.e., the experiment involves finite trails) following a "sampling without replacement", the probability of obatining a red ball (i.e., the success probability) changes for each drawn marble.
Thus the variable, "
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