Four persons can cross a bridge in 3, 7, 13, 17 minutes. Only two can cross at a time. Find the minimum time taken by the four to cross the bridge.

• First send 17 and 13 min guys together. When 13 minutes guy reaches the other end of the bridge, the 17 min guy will be 4 minutes away from the end point. Then send 7 min guy. By the time 17 min guy crosses the bridge, the 7 minute guy will have traveled 4 minutes and require 3 moire minutes to cross the bridge. Then send 3 min guy. Both 3 min guy and 7 min guy will reach the end of the bridge at the same time. Hence the time required will be 17 min + 3 min = 20 minutes only.
• 7 years agoHelpfull: Yes(1) No(0)
• send 17 and 13 min guys first then after 13 send 3 min guy till this time 17 min guy has just 1 more min to cover now send the 7 min guy who will travel 1 min along with the 17 min guy and remaining 6 min alone so
  17+6=23 min
  
• 11 years agoHelpfull: Yes(0) No(3)
• Ans 20min
• 5 years agoHelpfull: Yes(0) No(0)