iran-konkur 2017 Q144

iran-konkur · Other · konkur-riazi_1396_specialized Principle of Inclusion/Exclusion
144. In a bag there are $7$ white beads, $5$ black beads, and $3$ green beads. We draw beads from the bag until we are sure we have at least $4$ white beads or $3$ black beads or $2$ green beads. What is the minimum number of beads drawn?
(1) $6$ (2) $7$ (3) $8$ (4) $9$
\textbf{144.} In a bag there are $7$ white beads, $5$ black beads, and $3$ green beads. We draw beads from the bag until we are sure we have at least $4$ white beads or $3$ black beads or $2$ green beads. What is the minimum number of beads drawn?

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(1) $6$ \hfill (2) $7$ \hfill (3) $8$ \hfill (4) $9$

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