+0

# question on a math competition, i know the answer, i don't know how to get to it

0
58
1
+28

A stack contains 7 green marbles and 3 red marbles. 2 marbles are taken from the sack w/out replacement. What is the probability of taking one green marble and one red marble (in any order)?

May 9, 2022

#1
+117498
+1

A stack contains 7 green marbles and 3 red marbles. 2 marbles are taken from the sack w/out replacement. What is the probability of taking one green marble and one red marble (in any order)?

P(Green followed by Red)  =  $$\frac{7}{10}*\frac{3}{9}=\frac{21}{90}$$

Now do something very similar to get the prob of a red followed by a green.