A recent poll found that 45% of eligible voters are planning to vote in favor of a new by-law. Suppose you randomly survey six voters. What is the probability that at least three of the voters plan to vote in favor of the new by-law?

13.2%
25.5%
30.3%
55.8%

Question

A recent poll found that 45% of eligible voters are planning to vote in favor of a new by-law. Suppose you randomly survey six voters. What is the probability that at least three of the voters plan to vote in favor of the new by-law?  

    13.2%
    25.5%
    30.3%
    55.8%

anonymous · Answer

@amistre64 this one is for you

anonymous · Answer

I think this is binomial distribution so you have to use the formula
$$\sum_{k=0}^{X}\left(\begin{matrix}n \ k\end{matrix}\right)p^k(1-p)^(n-k)$$

n = number of trials
p = probability of success
k = number of successes

anonymous · Answer

Or you can use the binomial distribution tables to find $$P(X \ge 3)$$ which is also $$1 - P(X \le 2)$$

amistre64 · Answer

i was thinking the P(X>=3) method :)