SOLUTION: Tim has 4 table tennis balls with small cracks. His friend accidentally mixed them in with 16 good balls. If Tim randomly picks 3 table tennis balls, what is the probability that a

Question 289839: Tim has 4 table tennis balls with small cracks. His friend accidentally mixed them in with 16 good balls. If Tim randomly picks 3 table tennis balls, what is the probability that at least 1 is cracked?
Not sure how to approach this problem/what formula to use.
My first thought was to multiply 4/20*3/20*2/20, but the answer I got (.003) obviously seems a little off. Help!
Answer by richwmiller(17219) (Show Source): You can put this solution on YOUR website!
1st or 2nd or 3rd is cracked
or means add
4/20+3/19+2/18
1/5+3/19+1/9
401/855=.469
after choosing the first there are only 19 left
RELATED QUESTIONS
Tim has 4 table tennis balls with small cracks. His friend accidentally mixed them in... (answered by ewatrrr)

Tyler buys some tennis balls for an upcoming match. He gives a third of them to his... (answered by MathTherapy)

If an urn has 11 white balls and 9 red balls, what is the probability that 5 randomly... (answered by CPhill,greenestamps)

1) There are 10 tennis balls in a box; 6 of them are new. Then two balls are taken from... (answered by ikleyn)

If an urn has 5 white balls and 6 red balls and 8 green balls, what is the probability... (answered by ikleyn)

Jack had 333 bags of golf balls with bbb balls in each bag; then his friend gave him 666... (answered by Alan3354)

Sohrab is taking a long walk. He always finds it interesting to see how many sidewalk... (answered by richwmiller)

There are 20 balls in a box (5 balls with A on them, 6 balls with B on them,8 balls with... (answered by solver91311)

The 20 balls in a box (5 Balls with A on them, 10 Balls with B on them, 7 Balls with C on (answered by solver91311)