Disclosure: This question has been posted as Question 3 in Cracku Daily test by the name "Time Distance and Work Test 9" on 01/05/2017

For the question and solution, please visit the link given below

https://cracku.in/cq-cat-2017-free-time-distance-work-test-9

Alternate/Additional solution:

In the solution given, it has been assumed that R is still in his 1st round when P finishes 3 laps. However, another case can be put forth wherein R is in his 2nd round and gets to Q's position. This way the ratio comes out to be 4:3. So the question has two valid answers

On second thought, by the use of options 4:3 can be eliminated as being the answer. Just wanted to share the second solution in case some people might have missed it.