WBJEE · Maths · Probability
A rifleman is firing at a distant target and has only \(10 \%\) chance of hitting it. The least number of rounds he must fire to have more than \(50 \%\) chance of hitting it at least once, is
- A 5
- B 7
- C 9
- D 11
Answer & Solution
Correct Answer
(B) 7
Step-by-step Solution
Detailed explanation
Hint: \(\mathrm{P}\) (hitting a target) \(=\frac{1}{10}\) \(\therefore \mathrm{P}(\) not hitting a target \()=\frac{9}{10}\) \(\therefore\) Let number of trials \(=n\) So, \(\mathrm{P}(\) hitting at least once \()=1-\mathrm{P}\) (missing all)…
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