Hello, dominion!

I assume that the choosing is doneA survey is carried out on a group of 100 students, 60 of whom are boys.

Find the probability that any 2 students chosen at random from the original group will be both girls.replacement.without

There are: 60 boys and 40 girls.

Method #1

There are: . possible pairs of students.

To choose 2 girls, there are: . ways.

Therefore: .

Method #2

The probability that the first student is a girl is: .

The probability that the second student is a girl is: .

Therefore: .