JEE MAIN - Mathematics (2019 - 10th April Evening Slot - No. 5)
Minimum number of times a fair coin must be tossed so that the probability of getting at least one head is
more than 99% is :
6
5
8
7
Explanation
$$1 - {\left( {{1 \over 2}} \right)^n} > {{99} \over {100}}$$
$${\left( {{1 \over 2}} \right)^n} < {1 \over {100}}$$
$$ \Rightarrow $$ n = 7
$${\left( {{1 \over 2}} \right)^n} < {1 \over {100}}$$
$$ \Rightarrow $$ n = 7
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