Hi,

I have issues understanding probability.

I have this problem:

A device for checking welds in pumps is designed to signal if the weld is defective. If the weld is actually defective, the probability the device will give a signal is .94.

If the weld is actually not defective, the probability the device will give a signal is .05.

It is known that 3% of welds on pumps are defective. A weld is selected at random and checked by the device.

1- What is the probability the device will be correct?

2- Suppose the device gives a signal for the checked weld. What is the probability the weld is actually not defective (false positive)?

For the first question,

I did this:

P(device correct)=(.97)(.94)

The second I dont know what to do.

Please can someone help me ?