Question

If John has 20 marbles,10 red, 5 blue and 5 green.If his friend Jake took 2 marbles without looking and John took 1 what without looking what's the probability Jake took 2 reds marbles and John took 1 blue marble?

Answer 1

Answer: probability of Jake took 2 reds marbles = 3/52

probability of John took 1 blue marble = 1/8

Step-by-step explanation:

Okay, I will assume in this problem that the sample is not replacement, which means after Jake took 2 marbles, he didn't put it back into the sample.

The total of the sample = 20 + 10 +5 +5

Probability of Jake took the 1st red marble is 10/40 because there are 10 marbles in a whole bag of 40 marbles. Once Jack picked the 1st red marble out, there are only 9 red marbles left, thus the probability of the 2nd red marble is 9/39.

=> probability of Jake took 2 reds marbles = (10/40) *(9/39) = 3/52

and it goes the same way for John, except we only need to find 1 blue marble so we don't have to multiply anything here.

=> probability of John took 1 blue marble = 5/40 = 1/8