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(B) The probability of getting a head in a single toss is $p = \frac{1}{2}$,and the probability of getting a tail is $q = 1 - p = \frac{1}{2}$.The pro

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$3$

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(B) The probability of getting a head in a single toss is $p = \frac{1}{2}$,and the probability of getting a tail is $q = 1 - p = \frac{1}{2}$.The probability of getting no heads in $n$ tosses is $P(	ext{no heads}) = q^n = (\frac{1}{2})^n$.The probability of getting at least one head is $P(	ext{at least one head}) = 1 - P(	ext{no heads}) = 1 - (\frac{1}{2})^n$.Given that $1 - (\frac{1}{2})^n > 0.8$,we have:$1 - 0.8 > (\frac{1}{2})^n$$0.2 > (\frac{1}{2})^n$$\frac{1}{5} > \frac{1}{2^n}$$2^n > 5$.For $n = 2$,$2^2 = 4 For $n = 3$,$2^3 = 8 > 5$.Thus,the least value of $n$ is $3$.

$A$ coin is tossed $n$ times. The probability of getting a head at least once is greater than $0.8$. Then,the least value of such $n$ is:

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