- #1
Kites
- 39
- 0
I say urgent because of the horribly small lecture I received on this section, a whole 3 minutes or so of examples. While I won't give further context I can say without a doubt I am completely lost.
Here is the problem I am stuck on.
In a string of 12 Christmas tree light bulbs, 3 are defective. The bulbs are selected at random and tested, one at a time, until the third defective bulb is found. Compute the probability that the third defective bulb is the:
a) Third Bulb Tested
b) Fifth Bulb Tested
c) Tenth Bulb Tested
I am at a lost. My only feeble attempt at a solution has been: (1/12)*(1/11)*(1/10), which I know for a fact is wrong. If someone could shed some light, any light, on how to tackle problems like this I would be eternally grateful.
Here is the problem I am stuck on.
In a string of 12 Christmas tree light bulbs, 3 are defective. The bulbs are selected at random and tested, one at a time, until the third defective bulb is found. Compute the probability that the third defective bulb is the:
a) Third Bulb Tested
b) Fifth Bulb Tested
c) Tenth Bulb Tested
I am at a lost. My only feeble attempt at a solution has been: (1/12)*(1/11)*(1/10), which I know for a fact is wrong. If someone could shed some light, any light, on how to tackle problems like this I would be eternally grateful.