I can't believe I pulled that one out but here is how I did it.

I figured 60kts is one mile a min so it would take 50 min. 120 would be 25 min and 240 would be 12.5 min. I knew I was going 250 not 240 so I just said 12 min. After the interview I figured 50 is one fifth of 250 therefore it would take one fifth of an hour. 60 divided by 5 is 12 miles.

I still did not get the job. (United)