Answer:
5.13 feet
Explanation:
So, we have the full dimensions of flag #1, and we have the partial dimensions of flag #2, which should follow the same ratio as flag #1, since not indicated otherwise.
When you need to compare dimensions like that, the easiest way to proceed is to do a cross-multiplication. Let's say x is the length of flag #2 we're looking for. It's ratio over the width of flag #2 will be the same as the ratio of the length of flag #1 over its width, so:

If we isolate x, we have x = (2.7 * 1.9) / 1 = 5.13 feet
Which makes sense since we know the result should be a bit less than 2.7 times 2.