Question

There are 7 yellow, 6 blue, 9 red, and 3 green ribbons in a drawer. Once a ribbon is selected, it is not replaced. Find each probability.

P(a yellow ribbon and then a blue ribbon)


P(a yellow ribbon and then a blue ribbon)


a. 7/100
b. 42/635
c. 7/120
d. 7/125

Answer 1

A:
`(7)/(100)`

Explanation:

There are 25 ribbons total. The probability would be out of the 25 ribbons.

(1):

Yellow:
`(7)/(25)`

Blue:
`(6)/(25)`

Red:
`(9)/(25\\)`

Green:
`(3)/(25)`

When removing a ribbon that can't be replace, it'll leave you with a total of 24 ribbons.

(2):

Yellow:
`(6)/(24)=(1)/(4)`

Blue:
`(5)/(24)`

Red:
`(8)/(24)=(1)/(3)`

Green:
`(2)/(24)=(1)/(12)`

Multiply {(1) × (2)}:

Yellow:
`(7)/(25)` ×
`(6)/(24)` =
`(7)/(100)`

Blue:
`(6)/(25)` ×
`(5)/(24)` =
`(1)/(20)`

Answer 2

7/100

Explanation:

7 yellow, 6 blue, 9 red, and 3 green ribbons in a drawer

Total ribbons = 25 ribbons

P( yellow) = yellow / total = 7/25

Then not replaced

6 yellow, 6 blue, 9 red, and 3 green ribbons in a drawer

Total ribbons = 24 ribbons

P( blue) = blue / total = 6/24 = 1/4

P(a yellow ribbon and then a blue ribbon) = 7/25 * 1/4 =7/100