It took Esteban 1 minute and 20 second to travel one mile. If he then drives this one-mile distance in 55 seconds, how much faster is he driving in mile per hour?

Question

 Help me!!!

Answer 1

1min 20s is 80 seconds. 1mi in 80 seconds. 1mi in 55 seconds is 80/55=16/11=1.4545 as fast.

1mi in 80 seconds is 1mi in 80/3600 of an hour, so mph=3600/80=45mph.

1mi in 55 seconds is 16/11 * 45=720/11=65.4545 mph.

Or, 55 seconds is 55/3600 of an hour, so mph=3600/55=720/11=65.4545 mph.

The difference is 20.45 mph approx.