Highway Math

After years of going down highway 580, Parker finally says today, "The next exit is for Lakeshore Blvd!" I complimented his reading and asked if he could read the next sign. He could saying proudly, "Grand Avenue something mile." Considering the something was 1/4, I was a bit surprised he didn't know that fraction (since he does). So I said, "that is a quarter mile until the Grand Avenue exit." Then he asks without skipping a beat...

"So if we were going 60 miles per hour, it would take 15 seconds to get to Grand Avenue?"

Yes, Parker, that is correct.