Question

What is the probability of drawing yellow marble followed by a red marble from a bag containing 12 yellow marbles, 14 red marbles, and 15 green marbles if the first marble is not replaced?



18/43

21/205

192/1,849

Answer 1

I got 18/43..?

Answer 2

total number of marbles = 12 +14+15 = 41
as there are 12 marbles what do you think the probability of drawing a yellow one is

Answer 3

18/43 is not correct

Answer 4

the probability of frist drawing a yellow is 12/41

be cause there are 12 yellows in a total of 41 marbles

do you follow that?

Answer 5

But there is no answer choice for that

Answer 6

i know that is on;y the first part of the answer - but you do follow that right?

Answer 7

Yes i understand

Answer 8

ok - so thats not replaced so there is now 40 marbles for the second draw

and there are 14 red marbles

so in a similar way to to drawing the yellow one , can you work out the probability of drawing a red marble?

Answer 9

just 14/40?

Answer 10

for the yellow we had 12 yellows and total 41 - probability 12/41
now for the red we have 14 reds and total of 40 - probability of ?

Answer 11

yes right 14/40

Answer 12

that the second half of the problem

Answer 13

There is a law of probibilty which states that for 2or more independent events the probabilty of the 2 occurring are MULTIPLIED

the 2 events here are the yellow draw then the red and they are independent of each other

so probability( yellow then red ) = 12/41 * 14/40
which if you use ur calculator you'll find it comes to 21 / 205

Answer 14

Okay I see, Thank you for explaining! much simpler than it looks!

Answer 15

it is