I seem to have a bit of trouble with Probability, so this thread will contain most of my probability questions
The chance that a harvest is poorer than average is 0.5, but if it is known that a certain disease D is present, this probability increases to 0.8. The disease D is present in 30% of the harvests. Find the probability that, when the harvest is observed to be poorer than average, the disease D is present.
Alright so I managed to extract the following information from the above sentence.
Then from that sentence I understood it to be
which I ended up solving like so
But the answer in the back of the book is
and I have no idea where I went wrong heh
Nikki manufacture shoes in two separate factories at Alphaville and Betatown. The Alphaville plant produces 80% of the total output, with 10% defective, while the Betatown plant produces 20% of the output with 15% defective. Find the probability that the shoe found to be defective comes from the Betatown plant.
Alright so I thought that the above question was asking us to find
which I found out to be
But according to my teacher they are asking us to find
which I couldn't understand why they wanted us to find that, just trying to get my head around the situation really
Thanks