Rupert just told his brother Melvin that he would build him a picnic table by tomorrow. He needs to drill and saw in the back yard. He has 2 drills, either would do the job: a cordless drill and one that requires and extension cord. He is not sure the extension cord is still good or if the drills work. He estimates the reliabilities of these at:
RCordlessDrill = .7, RDrillWithCord = .9, RExtensionCord = .8.
He also has two saws, again, either would do the job: again a cordless saw, and one that would require the same extension cord. He estimates the saw reliability at:
RCordlessSaw = .75, RSawWithCord = .85.
The cord stays the same.
What is the chance (reliability) that Rupert can do the job (just considering tool reliability, not whether he has the skills)?