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Question
A coin is tossed thrice and all the eight outcomes are assumed equally likely. In which of the following cases are the following events A and B are independent?
A = the first throw results in head, B = the last throw results in tail.
Solution
\[S = \left[ \left( H H H \right) \left( H H T \right) \left( H T H \right) \left( H T T \right) \left( T H H \right) \left( T H T \right) \left( T T H \right) \left( T T T \right) \right]\]
\[P\left( A \right) = \frac{4}{8} = \frac{1}{2}\]
\[P\left( B \right) = \frac{4}{8} = \frac{1}{2}\]
\[\text{ Now } , \]
\[P\left( A \cap B \right) = \frac{2}{8} = \frac{1}{4}\]
\[ P\left( A \cap B \right) = P\left( A \right)P\left( B \right)\]
\[\text{ Thus, A and B are independent events. } \]
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