• Welcome! The new FreeMathHelp.com forum is live. We've moved from VB4 to Xenforo 2.1 as our underlying software. Hopefully you find the upgrade to be a positive change. Please feel free to reach out as issues arise -- things will be a little different, and minor issues will no doubt crop up.

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

sdd24

New member
Joined
May 11, 2017
Messages
5
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
 

tkhunny

Moderator
Staff member
Joined
Apr 12, 2005
Messages
9,697
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?
 

HallsofIvy

Elite Member
Joined
Jan 27, 2012
Messages
4,716
If \(\displaystyle 1- P^n= 0.5\) then \(\displaystyle 1- 0.5= P^n\) or \(\displaystyle P^n= 0.5\). Taking the logarithm of both sides, \(\displaystyle log(P^n)= n log(P)= log(0.5)\).
 
Top