IMO: Answer is
E (Let's wait for OA)How long did it take Carlos to drive
nonstop from his home to Atlanta, Georgia?
(1) Carlos's average speed for the trip was 55 miles per hour.
d=speed*t-------(1)
Here, average speed is given
It might be the case that Carlos's has taken a break in between.It is not mentioned that, he drove non stop. The time which we will get from the formula includes break time as well.
Anyway, it is
INSUFFICIENT in both the cases.
(2) If Carlos's average speed for the trip had been 20 percent faster, the trip would've taken 3 hours.
same for this, alone itself is
INSUFFICIENT1 and 2 combinedWe won't be able to get nonstop time, as it is not mentioned that Carlo's travelled non-stop and the speed given is obtained from non stop travel.
He might have travelled at 100 m/h took rest for long time and again travelled at 80m/h making an average of 50m/h (distance travelled by time taken)
INSUFFICIENT