Direct Variation

Question

A train takes 20 minutes to cover a distance of 19km. The ratio of the speeds of this train and another is 3:4. How much time will the second train take to cover the same distance of 19 km? 

Answer 1

d=r*t

19=r*(20/60)

19=r*(1/3)

r=3*19

r=57 kph for the first train

ratio of the speeds of this train to another is 3:4

57/R=3/4

3R=4*57

3R=228

R=228/3

R=76 kph for the speed of the second train

d=r*t

19=76*t

t=19/76

t=1/4 of an hour

(1/4)*60=15 minutes for the second train to cover 19 km