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?
Sathishkumar P
13h
10 + 2 + 2 = 14
cuddlybhindi
2d
ex -
10+1+1+7+1+1+2 = 23
Anonymous
2d
21
cuddlybhindi
2d
ex -
They need to move at slower pace when traveling together as it is dark so let's consider 1 minute as...read more
Anonymous
2d
20
Senthil Kumar
4d
21
Senthil Kumar
4d
12 minutes
M RAVITEJA
5d
17 minutes
rebeccah too
7d
280 MINUTES
Anonymous
8d
17
VINAYANADH.V.R
8d
Answer is 17. A and B cross the bridge. A comes back. Time taken 3 minutes. Now B is on the other side.C and D cross the bridge. B comes back. Time taken 10 + 2 = 12 minutes. Now C and D are on the ot...read more
Mayur Jadhav
9d
2 + 1 + 10 + 2 + 2 = 17 minutes
Thus, the least time required for all four people to cross is 17 minutes.
Anonymous
12d
Answering 17 minutes a and b first cross the bridge in 2 minutes and a 1 minute again trouser balance 14 minutes in be and c slower they bridge cross in 10 minutes balance 4 minutes b again cross the ...read more
JEYA BELLA D
12d
Answer is 17. A and B cross the bridge. A comes back. Time taken 3 minutes. Now B is on the other side.C and D cross the bridge. B comes back. Time taken 10 + 2 = 12 minutes. Now C and D are on the ot...read more
Sahil Thakur
13d
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
13d
7mints
priti gupta
14d
10 minutes
Anonymous
17d
8 minutes
Anonymous
21d
25 minutes
Anonymous
21d
8
Anonymous
28d
17 minutes
Pranav Gangurde
28d
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
1mo
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
1mo
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
1mo
17 mins
Prachi Dhere
1mo
It will take 20 min time to cross the bridge.
dhanalakshmi jm
1mo
12 mins
Anonymous
1mo
17minute
Sejalkumari Rajeshbhai Chaudhari
1mo
10
Anonymous
1mo
17 minutes
Anonymous
1mo
Total 5 minutes lagega
Anonymous
2mo
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
2mo
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
1mo
ex -
who will go back to give them torch back?
Anonymous
2mo
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
3mo
17 min
RAHUL TIWARI
3mo
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
4mo
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
4mo
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
5mo
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
5mo
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.
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