# Thread: Probability Q: manufacturer finds only 1 of 350 TV sets is defective.

1. ## Probability Q: manufacturer finds only 1 of 350 TV sets is defective.

An electronic manufacture has found that only 1 out of 350 of is television sets is defective. You are ordering a shipment of television sets for the electronic store where you work. How many television sets can you order before the probability that you'll receive at least one defective TV set reaches 50%?

So first, I need to find 1-P(none are defective) to find what is defective.
1- P(349/500)^n

I know next, I have to do something with a log bu I cannot remember

2. Whence came the "500"? You should have 350.

What is "P"? That should not be there after you use it. Just 349/350 will do.

Okay, what value of 'n' makes that 1/2?

3. If $1- P^n= 0.5$ then $1- 0.5= P^n$ or $P^n= 0.5$. Taking the logarithm of both sides, $log(P^n)= n log(P)= log(0.5)$.