A fellow walks a half-mile in 7.5 minutes, how fast does he walk in mph? In m/s?

Question

Train track method 

Answer 1

I don't know what the "train track" method is but

 

.5 miles/7.5 min * 60 min/hr = 4 mph

 

4 miles/ 1hr = 1 m/100 cm * 2.54 cm/in * 12 in/ft * 5280 ft/mile * 4 mile/hr * 1 hr/60 min * 1 min/60 sec

I will leave the arithmetic to you.

 

The trick to unit conversions is to make the units work