# 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.

• Nov 5th, 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..

#### 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..

#### selvakumar_2008 Profile Answers by selvakumar_2008

• May 17th, 2008

ans is 57minutes

#### ashutosh148 Profile Answers by ashutosh148

• May 17th, 2008

forty

#### srilathapillapalem Profile Answers by srilathapillapalem

• May 23rd, 2008

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

• Jun 3rd, 2008

ten

#### sravani811 Profile Answers by sravani811

• Jun 3rd, 2008

23 min!

#### sree24d Profile Answers by sree24d

• Jun 4th, 2008

first 17 and 7 are send then after 7 min send 13 after 10 min send 3.

#### arjutendul Profile Answers by arjutendul

• Jun 9th, 2008

seventeen minutes

#### shafeekhussain Profile Answers by shafeekhussain

• Jun 18th, 2008

20minutes

#### sandeep_yeleti Profile Answers by sandeep_yeleti

• Jun 19th, 2008

twenty three

#### prabu elamuruguselvan Profile Answers by prabu elamuruguselvan

• Jul 14th, 2008

i don't know the answer bu ti have the suggestion

#### lavaniya Profile Answers by lavaniya

• Sep 18th, 2008

the minimum time taken is 10 minutes

#### velkanesh Profile Answers by 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..

#### vinodhani Profile Answers by 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

#### m_manic Profile Answers by m_manic Questions by m_manic

• Dec 9th, 2009

Send 13 and 17 first. After 13 min send 7. After 4 min send 3.

Total 13 + 4 + 3 = 20 min

#### sachinkiit Profile Answers by sachinkiit

• Feb 7th, 2010

Sequence ie 17,3=3min

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

• Mar 4th, 2010

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.

#### sravan547 Profile Answers by 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

#### prititripathi Profile Answers by prititripathi

• Nov 13th, 2010

ans is 20 min
first 17 n 7 den after 7 min 13 n after 10 min 3
so total time is 20

#### prititripathi Profile Answers by prititripathi

• Nov 14th, 2010

ans is 20 min

#### 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

#### 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.

#### 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!

#### Blaidd

• Jun 17th, 2015

3 carries 17: 3 minutes
7 carries 13: 7 minutes
Only 2 cross at any one time and all 4 get across in 10 minutes

#### nithya

• Aug 24th, 2016

24