A bridge will collapse in 17 minutes.

4 people want to cross it before it will collapse. It is a dark night and there is only one torch between them.

Only two people can cross at a time.

"A" takes a minute to cross.
"B" takes 2 minutes.
"C" takes 5
and "D" takes 10 minutes

How do they all cross before the bridge collapses?

• A+B ....... 2 mins....A stays there.
  B comes back ..2 min
  C+D .. cross in 10 mins
  A comes back in 1 min.
  A+B crossin 2 mins.
  Total time = 2+2+10+1+2=17 mins
• 13 years agoHelpfull: Yes(7) No(0)
• A+B ....... 2 mins....A stays there.
  B comes back ..2 min
  C+D .. cross in 10 mins
  A comes back in 1 min.
  A+B crossin 2 mins.
  Total time = 2+2+10+1+2=17 mins
• 13 years agoHelpfull: Yes(3) No(0)
• A and B cross the bridge first (2 min). B stays at the other end and A returns back (1 min). Now, C and D cross the bridge together (10 min) and B returns from the other end to the previous point (2 min). Finally, A and B cross the bridge (2 min). So, the total time taken is 2 min + 1 min + 10 min + 2 min + 2 min = 17 min.
• 13 years agoHelpfull: Yes(3) No(1)
• 1st A & B ll go other side,
  A ll come back and (C & D)ll go other side
  then B ll return to take A.
  total time taken=2+1+10+2+2
• 13 years agoHelpfull: Yes(1) No(2)
• 1st A & B ll go other side,
  A ll come back and (C & D)ll go other side
  then B ll return to take A.
  total time taken=2+1+10+2+2
• 13 years agoHelpfull: Yes(1) No(1)