Question

I have a college class of 150 students: 90 girls and 60 boys.

a) what is the probability of a girl randomly raising her hand to answer a question? Express your answer as a simplified fraction.

b) what is the probability of a boy randomly raising his hand to answer a question? Express your answer as a simplified fraction.

c) the girl who answered the question in part (a) cannot answer another question and is removed from the pool of students. What is the probability that another girl raises her hand to answer a question?

Answer 1

a)
`(3)/(5)`

b)
`(2)/(5)`

c)
`(89)/(149)`

Explanation:

a)
`(90)/(150) = (9)/(15) = (3)/(5)`

b)
`(60)/(150) = (6)/(15) = (2)/(5)`

c) The girl that raised her hand before must be removed from the total number of girls AND the total number of students. This makes the number of girls 90 - 1 = 89 and the number of students 150 - 1 = 149.

`(89)/(149)` cannot be simplified.