Question

There are 3 white marbles and 7 blue marbles in a bag. Jamie will randomly pick two marbles out of the bag without replacing the first one. What is the probability of Jamie picking a white marble and then a blue marble?

Answer 1

The probability of Jamie picking a white marble and then a blue marble is 7/30 or 23%

Explanation:

It is given that there are 3 white marbles and 7 blue marbles in a bag.

Total = 7 + 3 = 10 marbles.

When Jamie picks first marble there are 3 white marbles out of 10 marbles in the bag so the probability of Jamie picking a white marble would be = 3/10

Then he picks second marble without replacing the first marble, there are only 9 marbles left, so the probability of picking blue marble would be = 7/9

Therefore,
`(3)/(10)` ×
`(7)/(9)`

=
`(7)/(30)` or 23%

The probability of Jamie picking a white marble and then a blue marble is 7/30 or 23%