2019 AMC 10A Problem 4
Problem 4 of 25EasierAlgebraCounting & Probability
A box contains red balls, green balls, yellow balls, blue balls, white balls, and black balls. What is the minimum number of balls that must be drawn from the box without replacement to guarantee that at least balls of a single color will be drawn?
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Solution
Note that we can pull as many as balls of each color without ensuring that balls of one color are drawn.
This means that we can draw all of the black, white and blue balls, along with red, green, and yellow balls.
This gives us a total of We need to add one at the end, however, to ensure that we get that th ball of some color,
Thus, B is the correct answer.