Math Help - probability..

1. probability..

The probability of being left-handed is 0.12. If we sample 25 people at
random, what is the probability that exactly 2 people are left-handed?

how do i tackle this one? please

2. Originally Posted by decoy808
The probability of being left-handed is 0.12. If we sample 25 people at
random, what is the probability that exactly 2 people are left-handed?

how do i tackle this one? please
Have you learned binomial distribution?

There are C(25, 2) ways to choose two people out of 25. (This is the same as $\binom{25}{2}$, just different notation, easier to type in.) For each of these, the probability is $(0.12)^2(1-0.12)^{23}$.

3. You can use a binomial distribution.

Let X represent the number of left-handed people, where a left-handed person is considered as success.
Then, X ~ B(25, 0.12)

$P(X = 2) = \binom{25}{2} (0.88)^{25-2}(0.12)^2$

Hope it helps