Math help with probability?

Question

here are the questions:

a jar contains 12 blue marbles, 8 green marbles, and 5 yellow marbles. without looking you choose a marble at random.

what is the probability that on your second draw you select a blue marble if you drew a blue marble the first time without replacing it?

what is the probability that on your second draw you select a green marble if you drew a blue marble the first time without replacing it?

these are two seperate questions. when you answer this please show your work so i can know how you did them. thanks for your answers.

Answer 1

Probability = number of color you want left / total number left

1) You have 11 blue, 8 green, and 5 yellow left

11 blues out of 24 total

11/24

2) You have 11 blue, 8 green, and 5 yellow left

8 green out of 24 total

8/24 = 1/3

Answer 2

a. in total, you have : 12+8+5 = 25 marbles.

if you took a blue marble the frist time, you have 24 marbles in the jar, out of which 11 are blue (12-1 = 11).

as a general formula, we have:

the probability  = no. of successfull draws /  total no. of draws.

so in this case, we have : 11 / 24.

b. the probability that on your second draw you select a green marble if you drew a blue marble the first time without replacing it:

no of green marbles: 8. total no. of marbles: 24 ( we took a blue one out, the first time, without replacing it).

probability = 8/24 = 1/3.

Answer 3

The jar has 25 marbles (12 + 8 +5)

If you draw one marble (the first one), then there will be only 24 marbles left.

1) If the first one is blue, there will be only 11 blue marbles left.

So the probability of drawing another blue will be 11/24.

2) The probability that the second one is gree will be the 8 green marbles out of 24 left (8/24 = 1/3).