A bowl contains 5 red balls and 5 blue balls. A woman selects balls at random without looking at them. (a) How many balls must she select (minimum) to be sure of having at least three blue balls?

Question

Armando Weber

Mathematics

21 September, 05:23

A bowl contains 5 red balls and 5 blue balls. A woman selects balls at random without looking at them. (a) How many balls must she select (minimum) to be sure of having at least three blue balls?

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Answers (1)

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Madeline May · Answer 1

Answer: 8

Step-by-step explanation: As the woman is not looking and assuming that the probability of taking a red ball is the same of a blue ball, she must select 8 balls to be sure she has at least 3 blue balls.

Because at the case of selecting 5 red balls in the first 5 selects and to have at least 3 blue ones in her hand, she will select the third blue ball at selection number 8.