It has been shown that 45% of a certain group of people are left-handed. Find the probability that, among eight of these people, at least 4 are left-handed.

The probability that, among eight of these people, at least 4 are left-handed is ___. (Round to three decimal places as needed.)


Answer:
Given:

Probability of success $(p)=0.45$

Sample size $(n)=8$

Solution:
The probability that among eight of these people at least 4 are left-handed:
$\text{P}(x \geq 4) = \sum_{4}^{8} \binom{n}{x} \cdot p^x \cdot (1-p)^{n-x} = \sum_{4}^{8} \binom{8}{x} \cdot 0.45^x \cdot (1-0.45)^{8-x} = 0.523$

Final Answer:
The probability that among eight of these people at least 4 are left-handed $=0.523$

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