Ok nothing to do with finance - but is an entertaining puzzle for those who care:A person is stranded in an island (assume to be at the centre of a circle) surrounded by water. On land surrounding this pool of water is a goblin who can run 4 times faster than i can swim. What is the best possible escape route i have to avoid the goblin.

I think you should check out the brainteaser forum

QuoteOriginally posted by: pirzadaOk nothing to do with finance - but is an entertaining puzzle for those who care:A person is stranded in an island (assume to be at the centre of a circle) surrounded by water. On land surrounding this pool of water is a goblin who can run 4 times faster than i can swim. What is the best possible escape route i have to avoid the goblin.This wouldn't be something you were asked at an interview would it?

Is there a coconut tree at the center of the island, with hopefully a place where one may seek shelter/refuge?

You could always throw the coconuts at the goblin in that case.

the solution is straightforward (just requires brute force calculations) once you realise that the only route to escape is to divert from the line along radius at certain stagei assume throughout that neither you nor goblin does get tired (so speeds, or at least their ratio does not change)1) we need to solve the following equation (assuming circle radius is unity):[PI+ACOS(r)]/[r+SQRT(1-r^2)]>4where r is the fraction of radius where we 1st turn...r=0.15so, you turn 90degrees the direction the bad guy chosen to chase...2) once you turn, the "rational goblin" will choose to change direction to opposite of the first because if we continue swimming along chosen line he will get you...indeed after turning he will need to run: 4*r+PI -ACOS(r)=2.32 (less than 4x distance u need to swim (c 0.98))...3) therefore, if your goblin is 'rational' you turn again to the same direction as goblin is running once you pass r1 fraction of unit. r1 is the solution to the following:[PI/2+4r+ACOS(r1)]/[r1-r+SQRT(1-r1^2)]>4here {r1|r=0.15}=0.074) certainly if we do this manoeuve, the goblin (by that time we know it is 'rational mf*er') will change direction once more, since in this case it will need to run 3*PI()/2-ACOS(r1)+4r1-4r~2.89 -> less then 4x distance you need to swim (0.84), so we also turn after swimming r2 along that new line:[ACOS(r+r1)+PI-4*(r-r1)]/[SQRT(1-(r2+r)^2)-r1+r2]>4 -> r2=0.165) goblin again reverses derection (PI-ACOS(r2+r)+4*(r-r1+r2)<4*[SQRT(1-(r2+r)^2)-r1]we turn at r3...[PI/2+ACOS(r1+r3)+4*(r-r1+r2)]/[SQRT(1-(r+r3)^2)-r2-r1+r3]>4 -> r3=0.26if goblin turns the distance it must cover is 3*PI/2-ACOS(r1+r3)-4*(r+r2-r1-r3) which is more than 4X SQRT(1-(r+r3)^2)-r2-r1... u win...

please be aware that goblin may still get you once you're on terra firma (if you are as lousy a runner as swimmer)

Here is the answer:http://mathproblems.info/prob131a.htmOn that website, you can also find other interesting problems.

In my country the solution is very simple - we would beat the living shit out of the goblin. Survival of the fittest my friend.

I thought I had a solution to this here.