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.

Questions by lakshmienator

Editorial / Best Answer

Answered by: Stelone B R

  • Nov 4th, 2007


Send the 17 and 3 first.. After 3 min, send 7, after 10 minutes send 13... So within 17 min 3 persons crossed..They were 3,7 and 17 and the remaining person will cross the bridge in 6 another minutes.. Therefore total and minimum time required is 17+6=23 minutes..

Showing Answers 1 - 23 of 23 Answers

Stelone B R

  • Nov 4th, 2007
 

Send the 17 and 3 first.. After 3 min, send 7, after 10 minutes send 13... So within 17 min 3 persons crossed..They were 3,7 and 17 and the remaining person will cross the bridge in 6 another minutes.. Therefore total and minimum time required is 17+6=23 minutes..

velkanesh

  • Nov 8th, 2009
 

Ans: 20 minutes

   First send 17 and 7. After 7 minutes, 7 is at finish and 17 needs 10 more minutes to complete his travel. now send 13. After 10 minutes 17 reaches finish and 13 needs 3 more minutes to complete. now send 3. both 3 and 13 reach destination at the same time after 3 minutes. hence the time taken is 7+10+3=20 minutes..

  Was this answer useful?  Yes

vinodhani

  • Nov 25th, 2009
 

First 17 and 7 going so that 7 will reach in 7 min remain 10
Now 13 and 17 is going so that  17 I will reach in 10 min remain 3
Now 13 and 3 is going so that both reached in 3 min. so totall min to reach is 7+10+3=20

  Was this answer useful?  Yes

sachinkiit

  • Feb 7th, 2010
 

Sequence ie 17,3=3min

                        17,7=7min
                     17,13=13min
-----------------------------------------
                      Total=23 mins

  Was this answer useful?  Yes

They can cross in 20 minutes. First 17 and 7 can go after 7 minutes 13 can go mean while in 17 mins first 17 crosses then 3 will go.

  Was this answer useful?  Yes

sravan547

  • Oct 1st, 2010
 

13 and 17 at a time so max time is 17minutes
3 and 7 at a time so max time is 7 by adding these two we get the 17+7=24
so the minimum time taken by four persons is 24minutes

  Was this answer useful?  Yes

vinodhini

  • Oct 1st, 2012
 

first send d[17min] and c[13]min.. c finishes in 13min that time d left with 4min. so send b[7min].. at 17th min d finishes so send a[3].. so answer is 20min not 23 min

  Was this answer useful?  Yes

SUBHANKAR ARMAN

  • Oct 9th, 2012
 

At first persons with 17m and 13m start. When 13m finish, 7m starts. There are remaining 4 minutes when 17m and 7m are walking together. After 4 minutes 17m finish and 7m is still walking for 3min. But during these 3minutes 3m starts and is walking with 7m. They finish in 3 minutes both. So there is total 17+3 minutes=20 minutes.

  Was this answer useful?  Yes

kuldeep

  • Dec 20th, 2012
 

at 0th minute, send 3,7.
at 3rd minute, send 17.
at 7th minute, send 13.
at 20th minute, all sent!

  Was this answer useful?  Yes

Give your answer:

If you think the above answer is not correct, Please select a reason and add your answer below.

Answer Question

Click here to Login / Register your free account


 
Send   Reset

 

Related Answered Questions

 

Related Open Questions