Everyday Sachin exercises for 2*1/2 hours. He exercises by walking, jogging and running. His speeds while walking, jogging and running in the ratio 1:2:4.Which of the following statements are true?

I. If he spends equal time on the three activities, then he runs twice the distance that he jogs.

II. If he runs at 8km per hour and distance covered by running and jogging together is 12km,then he walks a distance of 1km in 1 hour.

III. If the time for which he walks, jogs and runs is in the ratio 2:2:1 and he covers a total distance of 10km, then his speeds while walking, jogging and running are 2km/hr,4km/hr and 8km/hr respectively.