1. Let us assume a head-on elastic collision occurs between two objects (A and B) having masses ma and mg respectively, on a line. Both the objects
have initial velocities Vox and Vos before collision Applying conservation
of momentum derive the general expression for the final velocities Vox and
VfB of both.

when jerome paddle in flowing river towards east the net speed of jerome will increase

so the net speed of jerome will be given as

now the speed of paul will be same as it is given as he is running on the ground

so

so here we can say since the speed of jerome is more so he will win the race

now as we know the distance so the time difference is given as

so jerome will reach first and the time difference will be 203.55 s or 3.4 min