TS EAMCET · Maths · Probability
A coin is tossed \(n\) times the probability of getting head at least once is greater than 0.8 . Then, the least value of such \(n\) 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 head \(=\frac{1}{2}\). The probability of getting head atleast once in \(n\) times. \(=\frac{1}{2}+\frac{1}{2^2}+\ldots+\frac{1}{2^n}=\frac{\frac{1}{2}\left(1-\left(\frac{1}{2}\right)^n\right)}{1-\frac{1}{2}}\) \(=1-\left(\frac{1}{2}\right)^n\) Given…
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