Question

Of the 15 students (9 boys and 6 girls) in the sixth grade class at St.Andrew School, five students were absent Thursday.

a.) What is the probability that two of the absent students were girls?

b.) What is the probability that two of the absent students were boys?

c.) What is the probability that all the absent students were boys?

d.) What is the probability that none of the absent students were boys?

Answer 1

Before solving this question I believe you should know the below concept.

The formula for nCr = n!/((n-r)!*r!)

Hence say 6C2 = 6!/(4!*2!)= 15

Now let's solve the question

15 students

9 boys

6 girls

Absent = 5

a) P(2 girls absent & 3 boys absent) = 6C2*9C3/15C5 = 0.4195804

b) P(2 boys absent & 3 girls absent) = 6C3*9C2/15C5 = 0.2397602

c) P(5 boys absent) = 9C5 / 15C5 = 0.04195804

d) P( 0 boys absent & 5 girls absent) = 6C5 / 15C5 = 0.001998002

Hope the above answer has helped you in understanding the problem. Please upvote the ans if it has really helped you. Good Luck!!