Question

Emma selects markers from a bag without looking at them. The bag has 8 green markers, 4 red markers, and 3 blue markers. What is the probability that she selects a red, does not replace it and then selects a blue marker.

Answer 1

`(3)/(14)`

Explanation:

Given,number of red markers=
`n_(r)`=4

number of green markers=
`n_(g)`=8

number of blue markers=
`n_(b)`=3

`probability=\frac{\text{number of favourable outcomes}}{\text{total number of outcomes} }`

Let
`p_(1)` be the probability of getting a red marker=
`\frac{\text{number of red markers}}{\text{total number of markers}}`

So,
`p_(1)`=
`(4)/(8+4+3)=(4)/(15)`

Let
`p_(2)` be the probability of getting a blue marker after getting a red marker.

After removing a red marker,
`n_(r)` becomes 3 and
`n_(g),n_(b)` remain same.

`p_(2)=`
`(3)/(8+4+3)=(3)/(14)`

Probability for getting a red marker followed by getting a blue marker is
`p_(1)* p_(2)=(4)/(15)* (3)/(14)=(2)/(35)`