Companies MPL, QS and RobotS supply machine parts in a 5:3:2 ratio respectively. 0.2% of the parts from MPL are defective. 0.1% are defective from QS and 0.5% are defective from RobotS.

For two machine parts chosen at random, calculate the probability that:

a) Both are supplied from MPL and both are defective.

b) Both supplied by one of the other companies and found to be defective.

(Being stupid I know, but blanked on this.)

Thank you.