JEE Main 2021 (Online) 25th July Evening ShiftQuestion 1
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 $\_\_\_\_\_\_$ .
Probability
Answer$4$
Solution
$1-\left(\frac12\right)^n\ge0.9\Rightarrow2^n\ge10\Rightarrow n\ge4$. Minimum $n=4$.