Question 1018149
Make a table, which makes it easier.  Use large numbers to limit decimals
place=====good======defective===total
JC========9935========65=======10000
KC========9890=======110=======10000
BUT, they aren't equal, so I will increase to 100,000 and make JC 51000
=========50668.5=====331.5=====51000; multiplying the above cells by 5.1
=========48461=======539=======49000; multiplying the above b 4.9
=========98129.5=====870.5====100000
Given that the part is defective (870.5 out of 100000), the probability it came from JC is 331.5/870.5=0.3808
Intuitively it is a little more likely because a little more is made there; however, it is less than 2/3s as likely on a per unit basis, so the probability should be less than half.