An urn contains 5 red and 2 black balls. Two balls are randomly drawn. Let X represent the number of black balls. What are the possible values of X? Is X a random variable?
A
0, 1, 2
B
3, 5, 7
C
7, 7, 8
D
1, 5, 7
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A
0, 1, 2
The two balls selected can be represented as BB, BR, RB, RR, where B represents a black ball and R represents a red ball.
X represents the number of black balls.
$\therefore$ X(BB) = 2
X(BR) = 1
X(RB) = 1
X(RR) = 0
Therefore, the possible values of X are 0, 1 and 2.
Yes, X is a random variable.
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