iran-konkur 2020 Q146

iran-konkur · Other · konkur-riazi_1399_specialized_old-curriculum Probability Definitions Probability Using Set/Event Algebra
146- We have three urns. The first urn contains 9 white and 4 black marbles, the second contains 9 black and 4 white marbles, and the third contains 5 white and 5 black marbles. One marble is randomly drawn from one urn. What is the probability that at least one of these two marbles is black?
\[ (1)\quad \frac{1}{3} \qquad (2)\quad \frac{11}{18} \qquad (3)\quad \frac{25}{36} \qquad (4)\quad \frac{13}{18} \]
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\textbf{146-} We have three urns. The first urn contains 9 white and 4 black marbles, the second contains 9 black and 4 white marbles, and the third contains 5 white and 5 black marbles. One marble is randomly drawn from one urn. What is the probability that at least one of these two marbles is black?

\[
(1)\quad \frac{1}{3} \qquad (2)\quad \frac{11}{18} \qquad (3)\quad \frac{25}{36} \qquad (4)\quad \frac{13}{18}
\]



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