The probability that the sample of four balls contains two white balls and two red balls is 0.39.
Let E be an event a sample of selecting four balls from an urn are two red balls and two white balls.
According to the given question.
Total number of marbles in an urn = 17 + 20 = 37
Total number of white marbles = 17
Total number of red marbles = 20
Now, the number of ways of selecting four marbles form an urn =
And, number of ways of selecting 2 white and two red marbles =
As, we know that probability of an event is calculated by taking the ratio of total number of favorable outcomes to the total number of outcomes.
Therefore, the probability that the sample of four balls contains two white balls and two red balls is given by
⇒ P(E) = 5(19)(17)(16)/(37(3)(35)(17))
⇒ P(E) = 19(16)/37(3)(7)
⇒ P(E) = 304/777
⇒ P(E) = 0.39
Hence, the probability that the sample of four balls contains two white balls and two red balls is 0.39.
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