The correct answer I believe is 19 and not 17.

The slowest guy takes 10 minutes to go with the fastest guy.

The fastest guy take 1 minute to come back.

Now he goes with the guy that takes 5 minutes.

And 1 minute to go back.

Pick up the last guy and cross the bridge in 2 minutes.

Tot 19.

No matter the order as long as the fastest guy goes with another.

# Correct answer wrong

**anuran-roy**#2

Well, just a guess…That it asks for “total time taken by the 4 to cross the bridge” and not “the time elapsed between the first duo starting off and last duo reaching the other side”. Just a speculation…I may be wrong too

This is as follow

A - 1

B - 2

C - 5

D - 10

3 mins for A and B to go and A coming back

then , don’t send A , I think you will get it now…

Right Answer!!!

In first pass 1 and 2 will come and 1 go back

Then 5 and 10 will come and 2 go back

Finally 1 and 2 will come

Just think in the way that, if two people are together walking then the faster one speed is limited by slower one, and hence extra work has to be done if the slowest and the second slowest are moved separately.