csat-suneung 2009 Q28b

csat-suneung · South-Korea · csat__math-science 3 marks Combinations & Selection Combinatorial Probability

(Probability and Statistics) There are 9 balls in a bag, each labeled with a natural number from 1 to 9. When 4 balls are randomly drawn simultaneously from the bag, what is the probability that the sum of the largest and smallest numbers on the drawn balls is at least 7 and at most 9? [3 points]
(1) $\frac{5}{9}$
(2) $\frac{1}{2}$
(3) $\frac{4}{9}$
(4) $\frac{7}{18}$
(5) $\frac{1}{3}$

(Probability and Statistics) There are 9 balls in a bag, each labeled with a natural number from 1 to 9. When 4 balls are randomly drawn simultaneously from the bag, what is the probability that the sum of the largest and smallest numbers on the drawn balls is at least 7 and at most 9? [3 points]\\
(1) $\frac{5}{9}$\\
(2) $\frac{1}{2}$\\
(3) $\frac{4}{9}$\\
(4) $\frac{7}{18}$\\
(5) $\frac{1}{3}$

Paper Questions

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