Q from Gmat Prep 1

[smallsorrow]

A 2-day seminar: 90% of those registered attended the seminar on the first day, what percent of registered people did not attend on either day?

1. a total of 1000 people registered for the sem.
2. of those registered, 80% attended the sem on day 2

OA follows

[csandeepreddy]

1. INSUFF because it does not mention anything about day 2.
2. INSUFF because it does not mention % of people who attended on both the days. At the same time the 80% could be a subset of 90% or it could contain 10% of the people who did not attend on Day 1.

I think it should be E. Whats the ans?

[vin2k]

I was thinking B instead.

1 is Insuff as it gives no info on % of day 2
2 is sufficient.

Day 1 = .1X did not attend
Day 2 = .2X did not attend.

So what % did not attend on both days.
30% did not attend.. Although I am not too sure if my methodology is right.

[stubbornp]

imo E

[smallsorrow]

It is E.

I went for B, too ....