A slow jogger runs a mile in 13 min. Calculate speed in. a) in/s b) Km/h

(1mi=1609m); (1in=2.54),

The correct answers are A) 7.4 km/hr and B) 81.2 in/s.

Explanation:

A) The original ratio is 1 mi/13 min. We know that 1 mi = 5280 feet, so we have 5280 ft/13 min.

Each foot is 12 inches, so we have 5280*12 = 63360 in

63360 in/13 min

Each minute is 60 seconds; 13*60 = 780

63360 in/780 sec.

Dividing this, we get 81.2 in/sec.

B) 1 mi/13 min; 1 mile = 1609 m, so we have 1609 m/13 min.

1 m = 1000 km, so 1609 m = 1609/1000 = 1.609 km; this gives us 1.609 km/13 min.

An hour is 60 minutes, so we have 1.609 km / (13/60) hr; dividing this, we get 7.4 km/hr.