Question

A carpool contains three kindergartners and five first-graders. if two children are ill, find the probability that at least one of them is a kindergartner.

Answer 1

Solution: We are given that there are three kindergartners and five first-graders.

We have to find the probability that at least one of them is a kindergartner.

We know that:

P(at least one kindergartner) = 1 - P(no kindergartner) = 1 - P(all first-graders)

Now, P(all first-graders)$=\frac{5}{8} \times \frac{4}{7}=\frac{5}{14}$

Therefore, P(at least one kindergartner) $=1-\frac{5}{14}$

                                                                   $=\frac{14-5}{14}=\frac{9}{14}=0.643$