Question

I REALLY NEED HELP

Answer 1

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