GMAT Data Sufficiency (DS) | Re: Company X employs more than 5 people, and will choose 2 employees at

I'm confused as to why we're using combinatorics vs. probability.

I saw in the first response it assumed we have 10 people, but it says that there are MORE than 70% women so minimum 8.

Wouldn't we say for the first option
8/10 then the second 7/9 and multiply?

I see why it is E and the example of 1000 employees make sense...how are we to know this without trying multiple options?