Serge M. answered • 01/26/17

Tutor

5
(11)
Professor of Accounting, retired. Ph.D., CPA

The first cyclist traveled 22.5 km at 19 kph so he traveled 22.5/19 = 1.18421 hr

We can convert this to minutes: 60+1.18421 = 71.05 minutes or just 71 minutes

If the first cyclists time is X,the second cyclist leaves at X - 71 minutes

Now we set the two cyclists time equal to each other, multiplied by their respective speeds in minutes.

60*19 kphX = 60*28 kph(X-71)

1,140X = 1,680(x-71)

1,140X = 1,680X - 119,280

Solve for X

-540X = -119,280

X = -119,280 / -540 = 220.89 or about 221 minutes

It will take 221 minutes or 3 hrs and 41 minutes to catch up with the first cyclist.