There are 7 students in a class: 5 boys and 2 girls. If the teacher picks a group of 4 at random, what is the probability that everyone in the group is a boy?

probability that everyone in the group is a boy = 0.1428

Step-by-step explanation:

Here we have , There are 7 students in a class: 5 boys and 2 girls. If the teacher picks a group of 4 at random,  We need to find what is the probability that everyone in the group is a boy . Let's find out:

Initially we have ,  7 students out of which 5 boys, so probability  choosing first boy will be :

⇒

After this we are left with 6 students and 4 boys  , so probability  choosing second boy :

⇒

After this we are left with 5 students and 3 boys  , so probability  choosing third boy :

⇒

After this we are left with 4 students and 2 boys  , so probability  choosing fourth boy :

⇒

So, probability that everyone in the group is a boy = =

probability that everyone in the group is a boy = 0.1428

1/7

Step-by-step explanation:

5C4 ÷ 7C4

= 5/35

= 1/7