Question:
The probability of a man hitting a target is $\frac{1}{10}$.
The least number of shots required, so that the probability of his hitting the target at least once
is greater than $\frac{1}{4}$, is
Solution:
We have, $1-$ (probability of all shots result in
failure) $>\frac{1}{4}$
$\Rightarrow 1-\left(\frac{9}{10}\right)^{\mathrm{n}}>\frac{1}{4}$
$\Rightarrow \frac{3}{4}>\left(\frac{9}{10}\right)^{\mathrm{n}} \Rightarrow \mathrm{n} \geq 3$
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