Question

Twenty of the 50 digital video recorders​ (DVRs) in an inventory are known to be defective. What is the probability you randomly select an item that is not​ defective?

Answer 1

`3/5`

Explanation:

Remember that odds for plus odds against must be 1. Therefore, 20 out of 50 of the DVRs are defective, so 30 out of 50 would work. `30/50` simplifies into `3/5`, so that would be the probability of you picking out a DVR that works, and the probability of picking one that does not work would be the leftover `2/5` . Or, if you're answering with a percent, you would have a 60% chance of picking a working DVR.

I hope this helps, I know the explanation isn't really clear, but I can't really think of another way to explain it.