What is the minimum number of times a fair coin must be tossed so that the probability of getting at least one head exceeds 0.95?
What is the minimum number of times a fair coin must be tossed so that the probability of getting at least one head exceeds 0.95?
Solution
If the coin is tossed once, there will be choices i.e.
If the coin is tossed twice, there will be choices i.e.
If the coin is tossed thrice, there will be choices i.e.
There will only be one case of "all tails" (as shown in the boxed outcomes above).
Using the complement:
The probability of "at least one head" must exceed , so:
Let = number of coin tosses
: Probability of all tails
: Probability of all tails
: Probability of all tails
Since , the condition is satisfied.
Therefore, the minimum number of tosses is .
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BMSAT Kozhikode 2026
BMSAT Kozhikode 2026