Need help with DS question

[rainbownlife]

Division A of company X has 4850 customers.If there were 86 service errors in division A, what was the service-error rate , in number of service error per 100 customers, for division B of company X?
(1) overall service error rate for Div A dn B combined is 1.5 service errors per 100 customers.
(2) Div B has 9350 customers, none of who were customers of div a.

Why is (1) not sufficient?
Correct answer is : Both (1) and (2) together are sufficient.

[cris]

stm.1 would be SUFF if we knew that "none of the customers of div b were customers of div a"....but that info we get it in stm. 2

What is important of stm. 2) is that piece of info...no the total customers of div b. I think that if stm. 2 only said that none of the customers of div. b are customers of div. a C would s till be the answer.

Correct me if I am wrong.

[rainbownlife]

thanks for your response.

If this were a PS problem instead how would we go about solving it?
I guess i am just trying to nderstand what information is required to solve such a problem.
thanks so much !

[gmatguy16]

cris,can you please explain how stm.1 would be SUFF if we knew that "none of the customers of div b were customers of div a..
say Y is # of customers and y is # of service errors for division b from statement 1 we know ,(y+86)/(Y+4850)=0.15 so y/Y is unknown.