Question 981070: If a drawer has 4 red socks and 4 blue socks
a) If two are drawn what is the probability of a match?
b) If 3 are drawn what is the probability of a match?
c) What is the probability of having all one color after 4 draws?
This is what I have:
A) P (Red) on first draw = 4/8
P (Red) on second draw = 3/7
4/8 * 3/7 = 12/56
P (Blue) is the same so
12/56 + 12/56= 3/7
So answer = 3/7
B) 100% chance.
c) 4/8 +3/7 + 2/6 +1/5 ?
Any help is appreciated!
C) 4/8 + 3/7 + 2/6 + 1/5 ?
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! There are two ways to have a match with 2 drawn:
Probability both red = (4/8)*(3/7)=(12/56), as you wrote.
And same for blue, so sum is (24/56) as you wrote.
yes, 100% probability if 3 are drawn.
The 4 draws can be
RRRR (24/1680)=(1/70)
RRRB
RRBR
RRBB
RBRR
RBRB
RBBR
RBBB
BRRR
BRRB
BRBR
BRBB
BBRR
BBRB
BBBR
BBBB Same (1/70) probability
So the answer is their sum, or (2/70).
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