AP EAMCET · Maths · Probability
An unbiased coin is tossed \(n\) times. If the probability of getting atleast one head is greater than 0.8 , then the least value of \(n\) is
- A 2
- B 3
- C 4
- D 5
Answer & Solution
Correct Answer
(B) 3
Step-by-step Solution
Detailed explanation
The probability of getting at least one head \[ \begin{aligned} & =1-(\text { probability of getting no head) } \\ & =1-{ }^n C_n\left(\frac{1}{2}\right)^n=1-\left(\frac{1}{2}\right)^n>0.8 \text { (given), } \\ & \Rightarrow\left(\frac{1}{2}\right)^n 5 \end{aligned} \] The least…
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