A) 1/196
B) 2/7
C) 1/7
D) 13/56
E) 3/7
Correct Answer: C
Solution :
Required probability \[=P(WBWB)+P(BWBW)\] \[=\left( \frac{^{5}{{C}_{1}}{{\times }^{3}}{{C}_{1}}{{\times }^{4}}{{C}_{1}}{{\times }^{2}}{{C}_{1}}}{^{8}{{C}_{1}}{{\times }^{7}}{{C}_{1}}{{\times }^{6}}{{C}_{1}}{{\times }^{5}}{{C}_{1}}} \right)\] \[+\left( \frac{^{5}{{C}_{1}}{{\times }^{3}}{{C}_{1}}{{\times }^{4}}{{C}_{1}}{{\times }^{2}}{{C}_{1}}}{^{8}{{C}_{1}}{{\times }^{7}}{{C}_{1}}{{\times }^{6}}{{C}_{1}}{{\times }^{5}}{{C}_{1}}} \right)\] \[=\frac{1}{14}+\frac{1}{14}\] \[=\frac{2}{14}=\frac{1}{7}\]
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