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QJEEM21Ma3a55: JEE Main 2021 Mathematics - Class 12 JEEM21Ma3a55 Solution: A fair coin is tossed n-times such that the probability of…

A fair coin is tossed n-times such that the probability of getting at least one head is at least 0.9. Then the minimum value of n is ______________.

Step-by-Step Verified Solution

P(Head) = 12{1 \over 2}

1 −- P(All tail) ≥\ge 0.9

1−(12)n1 - {\left( {{1 \over 2}} \right)^n} ≥\ge 0.9

⇒(12)n≤110\Rightarrow {\left( {{1 \over 2}} \right)^n} \le {1 \over {10}}

⇒\Rightarrow nmin = 4

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