1+2- 2 mins
1 min to go back with flashlight
5+10- 10 mins
2 min guy go back with flashlight
1+2 = 2mins

total = 17 mins.

3 trips 2 return trips..

1 min and 2 min guy go over
1 min guy goes back
5 and 10 min guy go over
2 min guy goes back
1 and 2 min guy go over

= 17 mins altogether

I know nothing +1

Three friends check into a motel for the night and the clerk tells them the bill is $30, payable in advance. So, they each pay the clerk $10 and go to their room. A few minutes later, the clerk realizes he has made an error and overcharged the trio by $5. He asks the bellhop to return $5 to the 3 friends who had just checked in. The bellhop sees this as an opportunity to make $2 as he reasons that the three friends would have a tough time dividing $5 evenly among them; so he decides to tell them that the clerk made a mistake of only $3, giving a dollar back to each of the friends. He pockets the leftover $2 and goes home for the day! Now, each of the three friends gets a dollar back, thus they each paid $9 for the room which is a total of $27 for the night. We know the bellhop pocketed $2 and adding that to the $27, you get $29, not $30 which was originally spent. Where did the other dollar go????

This is something my friend asked me at work the other week and it took me ages to work it out - infact i never did..

but i think its actually a math fail..

In the sense that: you cant switch between counting down and counting up (10 to 9) (27 to 29)

When you count down you count down to 0.. Thus

29-1
28-2
27-3
26-4..

etc till
20-10
10-20
0-30

theres your thirty

Take The Letters D I S

Add One More Letter

DESI

pfft no fair, my english isn't good enough for wordgames, next!