View Full Version : Statistics probability
newjerz00
Mar 4, 2009, 04:35 PM
A shipment of 150 television sets contains 3 defective units. Find the probability of the vending company receiving (a) no defective units (b) all defective units and (c) at least one good unit?
galactus
Mar 4, 2009, 04:40 PM
How many TV's is the vending company getting? Is that given as well?
For instance, it might read, "A shipment of 150 television sets contains 3 defective units. If the vending company buys 10, find the probability of them receiving (a) no defective units (b) all defective units and (c) at least one good unit?".
newjerz00
Mar 4, 2009, 04:46 PM
No it just says
A shipment of 150 TV's contains 3 defective units. Find the probability of the vending company receiving (a) no defective units (b) all defective units and (c) at least one good unit
so they want three answers
galactus
Mar 4, 2009, 04:48 PM
Not much to it then. Wouldn't the prob. Of all defects be 3/150?
How many are not defects? Then, the prob. Of no defects would be \frac{\text{number not defective}}{150}
For 'at least one' defect, find the prob. Of no defects and subtract from 1.
newjerz00
Mar 4, 2009, 04:54 PM
That's what I had tried... or at least I think so..
The answers they give me are
a) 0.941 b)0.00000181 c)0.999998
galactus
Mar 4, 2009, 04:59 PM
a. No defects: \frac{147}{150}
b. all defects: \frac{3}{150}
I still think there is a piece of info missing from this problem as I mentioned earlier.
For 'at least one' good one, find the prob. Of no good ones and subtract from 1. But that is part a.
There is definitely something missing. I can tell from the answers you were given.
newjerz00
Mar 4, 2009, 05:02 PM
Thank youuu tons of help!
galactus
Mar 4, 2009, 05:10 PM
Your problem should be:
"A shipment of 150 television sets contains 3 defective units. If the vending company buys 3, find the probability of the vending company receiving (a) no defective units (b) all defective units and (c) at least one good unit?
all defects: \frac{C(3,3)C(147,0)}{C(150,3)}=.00000181
no defects: \frac{C(147,3)C(3,0)}{C(150,3)}=.9408