Question

Can you help me understand how to do this ?

Answer 1

Answer:

2/9

Explanation:

The number of ways to select x people from a group of n people is calculated as

$\text{nCx}=\frac{n!}{x!(n-x)!}$

Then, the number of ways to select 2 people from a group of 10 is:

$10C2=\frac{10!}{2!(10-2)!}=\frac{10!}{2!\cdot8!}=45$

So, there are 45 different ways to select two people.

On the other hand, the number of ways to select 2 boys is equal to

$5C2=\frac{5!}{2!(5-2)!}=\frac{5!}{2!\cdot3!}=10$

Because there are 5 boys.

Then, the probability that the teacher will chosse two boys is:

$P=\frac{10}{45}=\frac{2}{9}$

Therefore, the answer is 2/9