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In the SuperLottery, three balls are drawn (at random, without replacement) from white balls numbered from 1 to 12 and one SuperBall is drawn (at random) from red balls numbered from 13 to 20 When you buy a ticket, you choose three numbers from 1 to 12 and one number from 13 to 20.

If the numbers on your ticket match at least two of the white balls or match the red SuperBall, then you win a super prize. What is the probability that you win a super prize?

 

Please help ASAP... I know this is done with casework, but I just did like 20 other questions like this, so my brain is fried... crying

 Dec 3, 2023
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There are (312​)=220 ways to choose the three white balls on your ticket. For each of these choices, there is one way to choose the red SuperBall. There is also a way to choose the three white balls and the red SuperBall in the same order that they were drawn, so there are also (312​) winning ticket combinations in which your ticket matches at least two of the white balls drawn.

 

Finally, there are 8 winning ticket combinations in which your ticket matches the red SuperBall, but does not match any of the white balls drawn. Therefore, there are a total of 220+220+8=448 winning ticket combinations.

 

Since there are a total of (312​)⋅8=840 ways to choose three white balls and one red ball, the probability that your ticket is a winning ticket is 448/840 = 56/105​​.

 Dec 3, 2023

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