by Sage Pearce-Higgins Wed Apr 22, 2020 5:42 am
Yes, I wanted you to feel that tension: if something is countable, then it's quite hard to find a case in which we take non-integer quantity.
Nice example, and I can see that you're referring to SC 794 from OG2020. It's quite a clever problem as it trades on the fact that 'hours' are countable, but 'time' is uncountable. I'd look at this one quite simply: since we have a plural 'hours', then we need 'many'. We could write 'as much as 20 percent more time'. Your addition of a modifier to try to introduce a non-integer doesn't make a difference; the sentence is still discussing the countable 'hours'.
As for the inclusion or not of 'do', note that the OG example includes 'do', making clear that we're comparing the hours that one group fly, with the hours that another group fly.
Ending the sentence with the word 'do' alone after a comma sounds very clunky to my ears. Although I'm pretty sure GMAT wouldn't test you on this, I'd expect something like the following:
Pilots at Yak Airlines fly as many as 15 percent more hours per month than pilots at Yeti Airlines do, who fly 10 hours per month.