# Thread: Probability and TRANSFORMERS! yikes...

1. ## Probability and TRANSFORMERS! yikes...

ok so i got this weird question about transformers. its multiple choice but I cant seem to narrow down which of the two options it is. Note the answers are in Combination (C)

"In a shipment of 60 transformers, 15 are know to be defective. If 40 transformers are picked at random, what is the probability that all 40 are non-defective?"

A - C(40,40)/C(60,40)
B - C(45,40)/C(60,40)
C - C(40,40)/C(50,40)
D - C(45,25)/C(60,40)
E - None of the above

I am thinking its either A or B but I am not sure. Any help would be great. Thanks alot!

2. Originally Posted by IWasJustinYou
ok so i got this weird question about transformers. its multiple choice but I cant seem to narrow down which of the two options it is. Note the answers are in Combination (C)

"In a shipment of 60 transformers, 15 are know to be defective. If 40 transformers are picked at random, what is the probability that all 40 are non-defective?"

A - C(40,40)/C(60,40)
B - C(45,40)/C(60,40)
C - C(40,40)/C(50,40)
D - C(45,25)/C(60,40)
E - None of the above

I am thinking its either A or B but I am not sure. Any help would be great. Thanks alot!
The probability you seek is:

P=(45!/5!)/(60!/20!)

which is the same as B

RonL

3. thanks alot! i really appreciated that