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 ______________.
Answer (integer)
4
Solution
P(Head) = ${1 \over 2}$<br><br>1 $-$ P(All tail) $\ge$ 0.9<br><br>$1 - {\left( {{1 \over 2}} \right)^n}$ $\ge$ 0.9<br><br>$\Rightarrow {\left( {{1 \over 2}} \right)^n} \le {1 \over {10}}$<br><br>$\Rightarrow$ n<sub>min</sub> = 4
About this question
Subject: Mathematics · Chapter: Probability · Topic: Classical and Axiomatic Probability
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