# Probability questions

#### Awuah29

##### Christian predent
7+ Year Member
15+ Year Member
Anyone out there who know how to solve these two problems :

If two dice are rolled, what is the probability of rolling a total of 4?

There are 4 black balls and 7 white balls in a drawer. If two balls are drwan at random ( one after the other without replacement) what is the probability of selecting two black balls?

Thanks guys  #### busdriver

##### what do i know?
7+ Year Member
15+ Year Member
for the balls one:
11 balls total. 4 black balls. 4/11 times 3/10 should give you the probability of two black balls. so i guess 12/110 or 6/55

for the dice one. to get a total of four you can get 1 and 3, 2 and 2, and 3 and 1 so since there's 36 possibilites total for dice, it would be 3/36 or 1/12

please correct me if i'm wrong...it's been awhile since i've done probability...

#### sxr71

##### Senior Member
7+ Year Member
15+ Year Member
busdriver said:
for the balls one:
11 balls total. 4 black balls. 4/11 times 3/10 should give you the probability of two black balls. so i guess 12/110 or 6/55

for the dice one. to get a total of four you can get 1 and 3, 2 and 2, and 3 and 1 so since there's 36 possibilites total for dice, it would be 3/36 or 1/12

please correct me if i'm wrong...it's been awhile since i've done probability...

You're right!