- \frac{2}{7}
- \frac{2}{5}
- \frac{3}{7}
- \frac{1}{2}
- \frac{3}{5}
The probability of getting 2 yellow in a row is: \frac{2}{8}\frac{1}{7}=\frac{1}{28}.
The probability of getting 2 red in a row is: \frac{4}{8}\frac{3}{7}=\frac{6}{28}.
So the total probability is: \frac{1}{28}+\frac{1}{28}+\frac{6}{28}=\frac{2}{7}.
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Yup, starting tomorrow, I'll hide the answers behind spoiler tabs.
Using (n k) to stand for the binomial coefficient.
The answer is
(2 2) + (2 2) + (4 2)
---------------------
(28 2)
=
(# yellow pairs) + (# blue pairs) + (# red pairs)
-------------------------------------------------
(# total pairs)
We are choosing two socks each time, so we need to multiply the probability of choosing the first sock (something out of 8 with the prob. of choosing the second sock (something out of 7).
Paul, I like this blog. Perhaps you could hide the answers to the questions below a link?
Yup, starting tomorrow, I'll hide the answers behind spoiler tabs.
There's another way to do it.
Using (n k) to stand for the binomial coefficient.
The answer is
(2 2) + (2 2) + (4 2)
---------------------
(28 2)
=
(# yellow pairs) + (# blue pairs) + (# red pairs)
-------------------------------------------------
(# total pairs)
Uh, that should be (8 2) in the denominator. Durr.
Hey Paul, why we multiplied by 1/7 while getting the value for each of the socks.
We are choosing two socks each time, so we need to multiply the probability of choosing the first sock (something out of 8 with the prob. of choosing the second sock (something out of 7).
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