# Math Help - binomial distribution

1. ## binomial distribution

If 20% of the Aussie population are carriers of the gene for colour blindness, what is the probability that from a group of 7 people chosen at random, at least 3 will be carriers of the gene for colour blindnes??

Show working please =]

2. Originally Posted by bubbles73
If 20% of the Aussie population are carriers of the gene for colour blindness, what is the probability that from a group of 7 people chosen at random, at least 3 will be carriers of the gene for colour blindnes??

Show working please =]
$\Pr(X \geq 3) = 1 - \left( \Pr(X = 0) + \Pr(X = 1) + \Pr(X = 2) \right)$.

What have you tried? Where are you stuck?