   # A fair coin is tossed until a head comes up for first time. What is the probability of this happening on an odd tosses?

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A fair coin is tossed until a head comes up for the first time. What is the probability of this happening on an odd number tosses? posted Jun 26, 2018
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## 1 Answer

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Required Probability = 1/2(First coin turns heads) + 1/2^3 (third coin turns heads) + 1/2^5(Fifth coin turns heads + ..........
Required Probability = 1/2 + 1/2^3 + 1/2^5 + 1/2^7 + 1/2^9 ........
Required Probability = 1/2(1-(1/4)) = 2/3. answer Jun 28, 2018

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