Bridge and torch problem : Four people come to a river in the night. There is a narrow bridge, but it can only hold two people at a time. They have one torch and, because it's night, the torch has to be used when crossing the bridge. Person A can cross the bridge in 1 minute, B in 2 minutes, C in 7 minutes, and D in 10 minutes. When two people cross the bridge together, they must move at the slower person's pace. What is the least time taken for them to get across the bridge?
Sahil Thakur
2m
student at
Rayat & Bahra Institute of Engineering & Bio-Technology, Kharar
answer is 17 because here is 4 people a and b cross the bridge together with the speed of <2> mint or unke pass torch bhi hai and then A baapis jaayega torch dene C or D ke pass speed <1> and then C o...read more
Kamrul Hoda
11h
7mints
priti gupta
1d
10 minutes
Anonymous
4d
8 minutes
Anonymous
7d
25 minutes
Anonymous
8d
8
Anonymous
14d
17 minutes
Pranav Gangurde
15d
It will take 21 mins 10+1=10 (max time taken to cross bridge) 1=return time 7+1=7 (max time taken to cross bridge 2nd time) 1=return time 2 2+1=2 (max time taken to cross bridge 3rd time) 10+1+7+1+2=2...read more
sandeep ramini
19d
Ans is 17 mins Initial Crossing Person A and Person B cross the bridge together, taking 2 minutes (since B is slower). The torch is now on the other side.Returning the Torch Person A returns with the ...read more
Vishal Soni
23d
ex -
A and B cross (2 minutes): The fastest two go together. A returns (1 minute): The fastest person comes back with the torch. C and D cross (10 minutes): The slowest two go together. B returns (2 minute...read more
SUGANYA.G
25d
17 mins
Prachi Dhere
26d
It will take 20 min time to cross the bridge.
dhanalakshmi jm
28d
12 mins
Anonymous
29d
17minute
Sejalkumari Rajeshbhai Chaudhari
29d
10
Anonymous
1mo
17 minutes
Anonymous
1mo
Total 5 minutes lagega
Anonymous
1mo
पहिले A, B और c को ७ मिनट में पुल पार करेगा फिर वापिस आयेगा १
मिनट में फिर D को १० मिनट में पार करेगा । सभी लोगो को
पहुंचाने में १८ मिनट लगेगा ।
Anonymous
1mo
12 minutes because the a and b corss the bridge at same time then a and b corss the bridge in both corss the bridge in 2 minutes and c and d both cross bridge in 10 minutes so the total time is 10+2 =...read more
rythm31
23d
ex -
who will go back to give them torch back?
Anonymous
1mo
Total time taken will be 17 minutes
sarthak dhage
2mo
17= 2+1+10+2+2
Kiran Nayak
2mo
works at
Total time taken is :2+1+10+2+2= 17
Anonymous
2mo
All cross Brigade night =17 Minutes
VINOTH BABU
2mo
17 min
RAHUL TIWARI
2mo
1. A and B cross the bridge together (2 minutes). Torch is with them. 2. A returns with the torch (1 minute). Total time: 3 minutes. 3. C and D cross the bridge together (10 minutes). Torch is with th...read more
Mihir Vikram Singh Chauhan
3mo
10 min
A uses torch and crosses with B
That is 2 minutes.
Then A returns and crosses with C that is 7 minutes.
=> 2+1+7=10
Satya Narayana Reddy
3mo
17 minutes
Parvez Hakim
3mo
Step 1: A and B cross the bridge. A comes back. Time taken 3 minutes. Now B is on the other side. Step 2: C and D cross the bridge. B comes back. Time taken 8 + 2 = 10 minutes. Now C and D are on the ...read more
Anonymous
3mo
Sir, this question is wrong as long as it does not measure the length of the pool or the speed of the bucket.
Anonymous
4mo
B2
Anonymous
3mo
B2
Adithya CP
4mo
Total time taken will be 21 minutes
Anonymous
4mo
D
kiran babu
4mo
17 minutes
Sunita Tiwary
4mo
They will cross bridge in total 10 minutes. D will start with torch every time in his hand. First A will join him and reach other side of the bridge , followed by B who will reach the other side in 2 ...read more
Anonymous
4mo
A @ D will take to 10 minutes to cross the bridge so all of them will take 21 minutes to cross the bridge
Devika K.S
4mo
The bridge and torch problem (also known as The Midnight Train[1] and Dangerous crossing[2]) is a logic puzzle that deals with four people, a bridge and a torch. It is in the category of river crossin...read more
Hillan Shaba
4mo
currently not working
A&D will take 10 minutes to cross the bridge. So all of them will take 21 minutes to cross the bridge.
Praveen Singh
5mo
7 minutes with each for crossing the bridge.
Akshay Lilhare
5mo
Step 1: 2 minutes (A and B cross) Step 2: 1 minute (A returns) Step 3: 10 minutes (C and D cross) Step 4: 2 minutes (B returns) Step 5: 2 minutes (A and B cross again) Total Time = 2 + 1 + 10 + 2 + 2 ...read more
Anonymous
5mo
17 minutes
Hillan Shaba
5mo
currently not working
17 minutes
Ankit Pachauri
5mo
17 minutes with each for crossing the bridge
krishnakddinker9555
4mo
works at
How it solved
Anonymous
5mo
17 minutes
Piyush Bhatt
5mo
17 minutes
Anonymous
5mo
17 minutes
Venkatesh Karthik
5mo
The least time taken for all four people to get across the bridge is 17 minutes
opulentcornetto
5mo
currently not working
They are all cross the bridge 15 minutes everyone
Anonymous
5mo
A+B = 2
A returns = 1
C+D = 10
B returns = 2
A+B = 2
Total = 17 mins
naveen kumari
6mo
Step 1: 2 minutes (A and B cross) Step 2: 1 minute (A returns) Step 3: 10 minutes (C and D cross) Step 4: 2 minutes (B returns) Step 5: 2 minutes (A and B cross again) Total Time = 2 + 1 + 10 + 2 + 2 ...read more
Ekansh Agnihotri
6mo
-- A + B = 2min
-- A back = 1min
-- C + D = 10min
-- B back = 2min
-- A + B = 2min
-- Therefore 17 min
Anonymous
6mo
A and B cross in 2 minutes and C and D in 10 minutes.. This,least time taken=12 minutes..
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