Q:

# I REALLY NEED HELP1. There are 3 black marbles and 4 red marbles in a bag, what is the probability that you will pick a black marble out of the bag? Show your work 2. There are 3 black marbles and 4 red marbles in a bag, what is the probability that you will pick TWO black marbles out of the bag, without replacing the first one chosen? Show your work 3. There are 3 black marbles and 4 red marbles in a bag, what is the probability of picking a black marble, replacing it back in the bag, and then choosing another black marble, show your work

Accepted Solution

A:
1) marbles altogether = 3+4=7
P(black) = 3/7

2) P(first black marble)= 3/7
second black marble - When you removed 1st one only 2 black marbles are left and altogether marbles that are left = 6
P(second black marble) = 2/6=1/3
P(2 black marbles without replacement) means black and  black marbles without replacement.
P(2 black marbles without replacement) =3/7*1/3=1/7

3) P(first black marble)= 3/7
When you put that black marble back, you got again 3 black marbles and 4 red marbles in a bag. So,
P(second black marble)= 3/7
P(2 black marbles with replacement)=3/7*3/7= 9/49