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A teacher is making her students do the attendance. She has 3 blue ink pens and 9 black ink pens. The put the pen back every time it is used. What is the probability that the first three students will consecutively pick a blue ink pen?

 Oct 21, 2019
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We have 12 pens in total

 

P(first three pens are blue with replacement)  =  3/12 * 3/12 * 3/12  =

 

(1/4) * (1/4) * (1/4)   =

 

1/ 64

 

 

cool cool cool

 Oct 22, 2019

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