Four people need to cross a bridge at night with only one torch that can only illuminate two people at a time. Person A takes 1 minute, B takes 2 minutes, C takes 7 minutes, and D takes 10 minutes to cross. When two people cross together, they travel at the slower person's pace. What is the minimum time required for all four people to cross the bridge?
Krishnaraj
41m
21 min because Ist goes A and D it's take 10 min and A is come back 1 min IInd goes A and C it's take 7 min and A is come back in 1 min and IIIrd goes A and B it's take time is 2 min and add in I-11 m...read more
Lokanathan A
2h
17 minutes
Vishal Jaiswal
16h
2+2+10+1+2=17 Minute
Dre Antunes
1d
Based on the exact scenario given: 10 minutes. D goes in front with the torch and with whoever, A, B or C. They are illuminated, can see, and lead the way. The other 2 will follow right behind they sh...read more
Shivam Gupta
4d
Accross 17 minutes.
Anonymous
4d
2 (A+B) + 1 (A returns) + 10 (C+D) + 2 (B returns) + 2 (A+B again) = 17 minutes
prafull chintaman
6d
17 minute
1) A+b Cross = 2 min,
2) A return = 1 min,
3) C + D Cross = 10 min
4) B return = 2 min
5) A + B Cross = 2 min
Total = 17 min
shankey Kasar
7d
Optimal Strategy (Total = 17 minutes): 1. A and B cross together: time = 2 minutes (A and B on far side) 2. A returns with torch: time = 1 minute (A back, B stays) 3. C and D cross together: time = 10...read more
ARADHANA YADAV
7d
17 minutes
Diya Gahlot
10d
Total time 23 minutes
Anonymous
10d
17
Anonymous
28d
17 Minutes
Sukhi Sahu
1mo
10 minute
Shiva Akash
1mo
student at
Madras University
17 minutes
Anonymous
1mo
Step 1: A+B go → 2
Step 2: A returns ← 1
Step 3: C+D go → 10
Step 4: B returns ← 2
Step 5: A+B go → 2
Total = 2 + 1 + 10 + 2 + 2 = 17 minutes
Aditya Patel
1mo
Step 1: A+B go → 2
Step 2: A returns ← 1
Step 3: C+D go → 10
Step 4: B returns ← 2
Step 5: A+B go → 2
Total = 2 + 1 + 10 + 2 + 2 = 17 minutes
Anonymous
10d
17 is correct
DIVYA GUPTA
1mo
21 min because at a time two person can cross bridge first time = A and D go togather and ! will retun with tourch ( 10 +1 ) = 11 min sec time = A+C go togather and ! will retun with tourch ( 7 +1 ) =...read more
Dr. GOUTAM BANERJEE
1mo
works at
11 minutes
Anonymous
10d
How 11 minutes? One has to come back that time also you have to consider
Goutam Patar
1mo
2+1+7+1+10=21(assume A return always for taken others)
Mr. Rupesh Dnyaneshwar Buwa
1mo
23 min
Sandeep Gautam
1mo
17 min
ctrlnova
1mo
student at
University Department of Information and Communication Technology
21 mins
Anonymous
1mo
currently not working
23min
shrinathdwivedi
1mo
works at
Seaspeed Marine Services LLP
17 minutes
Megha Elsa
1mo
17 minutes
Layma
1mo
Last other two people can never crossed the bridge because first two people crossed the bridge with one torch now last two peoples haven't there torch so sorry for last two people 😔
cute sonali
1mo
Minimum 17 minutes required
Raj Goswami
1mo
15
Priya Vadivelan
1mo
10
sagar Kevant
1mo
17 minutes
Dhanush Srinivasan
2mo
17 minutes
Vvikas Biraree
2mo
17 mins
Riya
2mo
3+10+2=15
Avinash
2mo
17 minutes
Vaibhav Zemse
2mo
21
Sumit Kumar
2mo
Only 21 minutes
Sunil Kumar Pradhan
2mo
21
Suresh Rana
2mo
works at
12
Sathishkumar P
2mo
10 + 2 + 2 = 14
cuddlybhindi
2mo
currently not working
10+1+1+7+1+1+2 = 23
Anonymous
2mo
21
cuddlybhindi
2mo
currently not working
They need to move at slower pace when traveling together as it is dark so let's consider 1 minute as...read more
Anonymous
2mo
20
Senthil Kumar
2mo
21
Senthil Kumar
2mo
12 minutes
M RAVITEJA
2mo
17 minutes
rebeccah too
2mo
280 MINUTES
Anonymous
2mo
17
VINAYANADH.V.R
2mo
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
2mo
2 + 1 + 10 + 2 + 2 = 17 minutes
Thus, the least time required for all four people to cross is 17 minutes.
Anonymous
2mo
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
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