Data Sufficiency

2. IN 1995, Division A (DA) of Company X had 4,850 customers. If there were 86 service errors in DA that year, what was the service error rate, in number of service error per 100 customers, for Division B (DB) of company X in 1995?

i. In 1995 the overall service-error rate for DA and DB combined was 1.5 service-error per 100 customers?
ii. In 1995, DB had 9,350, none of whom were customers of DA.

OA C One quick question.What if the some customers of A overlaps with B customers in that 4850?
In 2, it is explicitly mentioned that among 9,350 no overlap exists.But it fails to present the same with A. So i chose E and i thought i nailed it

In 1995, DB had 9,350, none of whom were customers of DA
DA is not Company X. So it means, DB had 9350 employees of the Company X

Now 1+2, C is sufficient

Please correct me if am wrong!

GmatKiss wrote:In 1995, DB had 9,350, none of whom were customers of DA
DA is not Company X. So it means, DB had 9350 employees of the Company X

Now 1+2, C is sufficient

Please correct me if am wrong!

I think i lost you. Are you saying DA is not part of X??
But argument clearly says "Division A of Company X".

My question is how can rule out the overlap of Div A customers(4,850 ) with Div B customers. Reverse is ruled out explicitly in ii.

When you combine answers, the information applies to the total. If you know that B shares no customers with A, then you also know A shares no customers with B. You can't use that information when working with A alone, which is why you need to combine the statements.