NTA Abhyas JEE Main2020MathematicsProbabilityPractice

15 coins are tossed. If the probability of getting at least 8 heads is equal to p , then 8 p is equal to

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Correct answer

D. 16

Step-by-step solution

Probability of getting a head = 1 2 Probability of getting at least 8 heads = 15 C 8 1 2 8 1 2 7 + 15 C 9 1 2 9 1 2 6 + … … + 15 C 15 1 2 15 = 15 C 8 + 15 C 9 + - - + 15 C 15 2 15 = 2 14 2 15 = 1 2

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