JEE Mains · Maths · STD 12 - 13. probability
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 \(....\)
- A \(3\)
- B \(4\)
- C \(5\)
- D \(6\)
Answer & Solution
Correct Answer
(B) \(4\)
Step-by-step Solution
Detailed explanation
\(\mathrm{P}(\mathrm{Head})=\frac{1}{2}\) \(1-\left(\frac{1}{2}\right)^{n} \geq 0.9\) \(\Rightarrow\left(\frac{1}{2}\right)^{\mathrm{n}} \leq \frac{1}{10}\) \(\Rightarrow \mathrm{n}_{\min }=4\)
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