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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.

Asked by: lakshmienator | Member Since Aug-2007 | Asked on: Aug 20th, 2007

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Editorial / Best Answer

Answered by: Stelone B R

Answered On : 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

Answered On : 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..

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Ans is 57minutes

  
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ashutosh148

Answered On : May 17th, 2008

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forty

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May be 24min....once 13 and 17 will go...then 3 & 7..totally 17+7

  
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madure

Answered On : Jun 3rd, 2008

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ten

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sravani811

Answered On : Jun 3rd, 2008

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23 min!

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sree24d

Answered On : Jun 4th, 2008

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Answer is: 20 min first 17 and 7 are send then after 7 min send 13 after 10 min send 3.

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arjutendul

Answered On : Jun 9th, 2008

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Seventeen minutes

  
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shafeekhussain

Answered On : Jun 18th, 2008

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  20minutes

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sandeep_yeleti

Answered On : Jun 19th, 2008

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Twenty three

  
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I don't know the answer bu ti have the suggestion 3&17 is the answer

  
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lavaniya

Answered On : Sep 18th, 2008

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The minimum time taken is 10 minutes

  
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velkanesh

Answered On : Nov 8th, 2009

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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..

  
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vinodhani

Answered On : Nov 25th, 2009

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

  
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Send 13 and 17 first. After 13 min send 7. After 4 min send 3.Total 13 + 4 + 3 = 20 min

  
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sachinkiit

Answered On : Feb 7th, 2010

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Sequence ie 17,3=3min                        17,7=7min                     17,13=13min-----------------------------------------                      Total=23 mins

  
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pradeep9321

Answered On : Mar 4th, 2010

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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.

  
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sravan547

Answered On : Oct 1st, 2010

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13 and 17 at a time so max time is 17minutes3 and 7 at a time so max time is 7 by adding these two we get the 17+7=24so the minimum time taken by four persons is 24minutes

  
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prititripathi

Answered On : Nov 13th, 2010

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Ans is 20 minfirst 17 n 7 den after 7 min 13 n after 10 min 3 so total time is 20

  
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prititripathi

Answered On : Nov 14th, 2010

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Ans is 20 min

  
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vinodhini

Answered On : 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

  
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SUBHANKAR ARMAN

Answered On : 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.

  
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kuldeep

Answered On : Dec 20th, 2012

At 0th minute, send 3,7.
at 3rd minute, send 17.
at 7th minute, send 13.

at 20th minute, all sent!

  
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