csat-suneung 2011 Q17

csat-suneung · South-Korea · csat__math-humanities 4 marks Combinations & Selection Combinatorial Probability
There are 2 students each from Korea, China, and Japan. When these 6 students each randomly select and sit in one of 6 seats with assigned seat numbers as shown in the figure, what is the probability that the two students from the same country sit such that the difference in their seat numbers is 1 or 10? [4 points]
111213

212223

(1) $\frac { 1 } { 20 }$
(2) $\frac { 1 } { 10 }$
(3) $\frac { 3 } { 20 }$
(4) $\frac { 1 } { 5 }$
(5) $\frac { 1 } { 4 }$
There are 2 students each from Korea, China, and Japan. When these 6 students each randomly select and sit in one of 6 seats with assigned seat numbers as shown in the figure, what is the probability that the two students from the same country sit such that the difference in their seat numbers is 1 or 10? [4 points]

\begin{center}
\begin{tabular}{ | l | l | l | }
\hline
11 & 12 & 13 \\
\hline
\end{tabular}
\end{center}

\begin{center}
\begin{tabular}{ | l | l | l | }
\hline
21 & 22 & 23 \\
\hline
\end{tabular}
\end{center}

(1) $\frac { 1 } { 20 }$\\
(2) $\frac { 1 } { 10 }$\\
(3) $\frac { 3 } { 20 }$\\
(4) $\frac { 1 } { 5 }$\\
(5) $\frac { 1 } { 4 }$