There are 10 items in a box, out of which 3 are defective. 2 balls are taken one after the other. What is the probability that both of them are defective?

• total balls are =10
  sample space is 10c2
  in that 3 are defective balls so good balls are 7
  then when two balls are taken one after another ,both are defective so the probability of getting both are defective =3c2
  total probability=3c2/10c2=1/15
• 13 years agoHelpfull: Yes(7) No(0)
• The Prob. of getting a defective ball:
  When the first ball was taken=3/10
  When the next ball was taken=2/9
  The prob that both are defective=3/10*2/9=6/90 or1/15
• 13 years agoHelpfull: Yes(3) No(1)