A carton of 12 rechargable batteries contains one that is defective. In how many ways can the inspector choose 3 of the batteries and (a) get the one that is defective, (b)not get the one that is defective?
There are 2 defective batteries and 10 good batteries. a) none of the defective batteries (10C3) = 120 b) one of the defective batteries (10C2)(2C1) = 90
