Ketaki M. answered 08/10/15
Tutor
New to Wyzant
Ketaki M Math,SAT,ACT.GRE,AP CAlculus
so you already know that 87% of the times report B was pulled and 13% it was report A which was pulled.
so if we talk about only 100 files,87 are file B type and 13 are file A type ;being pulled.
now think if it was let us say 60 and 40 wouldn't you say that 20 files more(of type B) per 100 are being pulled .
similarly here it will be 87-13 ie 74 files of type B per 100 being pulled more than of type A
hence your answer should be 74%