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December 13th, 2012, 06:22 PM   #1
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Two Probability Questions, Stumped!

So I have these two probability questions and probability is my weakest subject. These are suppose to be simple but I cannot wrap my mind around it.

The first problem:

"Suppose a family wants to have 3 children. Find the probability that the family has at least 1 boy."

The second problem:

"If a marble is drawn from a bag containing 4 yellow, 5 red, and 3 blue marbles, what are probabilities of the following?

a. The marble is blue.

b. The marble is blue or red"

Help would be appreciated! Thanks
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December 13th, 2012, 06:42 PM   #2
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Re: Two Probability Questions, Stumped!

1.) It is certain given the couple has 3 children, that they will either have 3 girls (event A) OR at least 1 boy (event B). So we may state:

I am assuming the probability of having either gender is equal.

2.) There are 12 marbles total.

a) There are 3 blue marbles, so

b) There are a total of 8 blue or red marbles, so
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December 15th, 2012, 04:22 PM   #3
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Re: Two Probability Questions, Stumped!


B B B *
B B G *
B G B *
G B B *
G G B *
G B G *
B G G *

P(B) = 7/8.
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