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 Probability and Statistics Basic Probability and Statistics Math Forum

 May 14th, 2014, 07:07 AM #1 Member   Joined: Apr 2014 From: Missouri Posts: 39 Thanks: 1 2 person die roll 2 times If A and B both rolled two standard dice two times then what is the probability that B gets the same number as A but not necessarily in the same order? I don't understand the question. Can you please solve it? Thanks in advance and Regards May 14th, 2014, 12:25 PM   #2
Math Team

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Hello, Shen!

Quote:
 If A and B both rolled two standard dice two times then what is the probability that B gets the same number as A but not necessarily in the same order? I don't understand the question. $\displaystyle \;\;$Neither do I!

Because of the phrase "but not necessarily in the same order",
I believe it asked for the probability that B gets the same two numbers as A.

I listed the outcomes and counted.

$\displaystyle \quad \begin{array}{cccccc} 11 & 12 & 13 & 14 & 15 & 16 \\ 21 &22 & 23 & 24 & 25 & 26 \\ 31&32&33&34&35&36\\ 41&42&43&44&45&46 \\ 51&52&53&54&55&56\\ 61&62&63&64&65&66 \end{array}$

Suppose A rolls a "double".
This happens $\displaystyle \tfrac{6}{36} = \tfrac{1}{6}$ of the time.
Then B must match it; probability: $\displaystyle \tfrac{1}{36}$
$\displaystyle P(\text{Double and match}) \:=\:\tfrac{1}{6}\cdot\tfrac{1}{36} \:=\:\tfrac{1}{216}$

Suppose A rolls some "Other".
This happens $\displaystyle \tfrac{30}{36} = \tfrac{5}{6}$ of the time.
Then B must match it; probability: $\displaystyle \tfrac{2}{36}$
$\displaystyle P(\text{Other and match}) \:=\:\tfrac{5}{6}\cdot\tfrac{2}{36} \:=\:\tfrac{10}{216}$

Therefore: $\displaystyle \:P(\text{Match}) \;=\;\tfrac{1}{216} + \tfrac{10}{216} \;=\;\tfrac{11}{216}$ May 14th, 2014, 01:09 PM #3 Member   Joined: Apr 2014 From: Missouri Posts: 39 Thanks: 1 Hi soroban Thanks. This is the answer. I was stuck as i did not divide the double rolls and single rolls. Now i understand. Thanks again Tags die, person, roll, times Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Threads Thread Thread Starter Forum Replies Last Post Chikis Elementary Math 10 April 7th, 2014 05:40 PM AVS Algebra 8 September 21st, 2013 05:05 AM rtfanson Algebra 0 December 3rd, 2010 09:00 AM crOKaycomputer Advanced Statistics 1 May 10th, 2008 06:24 AM AVS Calculus 0 December 31st, 1969 04:00 PM

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