Basic probability help

Mechanical Engineering reported on the need for wireless networks to monitor the quality of industrial equipment. For example, consider Eaton Corp., a company that develops distribution products. Eaton estimates that 90% of the electrical switching devices it sells can monitor the quality of the power running through the device. Eaton further estimates that of the buyers of electrical switching devices capable of monitoring quality, 90% do not wire the equipment up for that purpose. Use this info to estimate the probability that an Eaton electrical switching device is capable of monitoring power quality and is wired up for that purpose.

I know that if you define the two events as A and B,
P (A) = .9
P (B/A) = .9

And I think the last part of the question is asking for P(A and complement of B), but from there I cannot figure out how to deduce what the probability of B is. I just can't figure out an equation that would work.

Thank you!
Last edited:


Ambassador to the humans
Hi! :welcome: We are glad that you posted here! This looks like a homework question though. Our homework help policy can be found here. We mainly just want to see what you have tried so far and that you have put some effort into the problem. I would also suggest checking out this thread for some guidelines on smart posting behavior that can help you get answers that are better much more quickly.