- Prepare
- All Platforms
- Programming
- Aptitude
- Syllabus
- Interview Preparation
- Interview Exp.
- Off Campus
- Prime Video
- Prime Mock

- Prime Video
- OffCampus Updates
- Placement Stats
- Prime Video
- Prime Mock

^{0}Notifications Mark All Read

No New notification

- Login
- Get Prime

# Crossing the Bridge Puzzle

## Crossing the Bridge

In Crossing the Bridge Puzzle, a bridge will collapse in 17 minutes. 4 people want to cross it before it will collapse. It is a dark night and there is only one torch between them. Only two people can cross at a time. “A” takes a minute to cross. “B” takes 2 minutes, “C” takes 5 minutes and “D” takes 10 minutes. How do they all cross before the bridge cross ?

## Solution

Here we have provided information for the solution of Crossing the Bridge Puzzle :

Time in which bridge will collapse = 17 mins

Number of people who wants to cross the bridge = 4 people

Number of the torch they have = 1

Time taken by A to cross the bridge = 1 minute

Time is taken by B to cross the bridge = 2 minutes

Time is taken by C to cross the bridge = 5 minutes

Time is taken by D to cross the bridge = 10 minutes

```
Move Time
A & B Cross with torch 2 min
A return with torch 1 min
C & D Cross with torch 10 min
B return with torch 2 min
A & B cross with torch 2 min
```

Total time 17 min

## Detail Analysis

A & B crosses the bridge in 2 mins and returns with the torch in 1 min, so the total time taken by now is 3 min.

**Time left before the bridge collapsed = 14 mins**

C & D crosses the bridge in 10 mins and B returns with the torch in 2 mins, so the total time taken by now is 15 min.

**Time left before the bridge collapsed = 2 mins**

Now, A & B were only left out and the time left before the bridge collapsed in 2 min but the maximum time taken by A & B to cross the bridge is 2 mins as the time taken by A is 1 min and by B is 2 mins.

**Hence A, B, C, and D four will cross the bridge within 17 mins.**

**Crossing the Bridge **

In Crossing the Bridge Puzzle, a bridge will collapse in 17 minutes. 4 people want to cross it before it will collapse. It is a dark night and there is only one torch between them. Only two people can cross at a time. “A” takes a minute to cross. “B” takes 2 minutes, “C” takes 5 minutes and “D” takes 10 minutes. How do they all cross before the bridge cross?

## Solution

Here we have provided information for the solution of Crossing the Bridge Puzzle :

Time in which bridge will collapse = 17 mins

Number of people who wants to cross the bridge = 4 people

Number of the torch they have = 1

Time taken by A to cross the bridge = 1 minute

Time is taken by B to cross the bridge = 2 minutes

Time is taken by C to cross the bridge = 5 minutes

Time is taken by D to cross the bridge = 10 minutes

```
Move Time
A & B Cross with torch 2 min
A return with torch 1 min
C & D Cross with torch 10 min
B return with torch 2 min
A & B cross with torch 2 min
```

Total time 17 min

### Detail Analysis

A & B crosses the bridge in 2 mins and returns with the torch in 1 min, so the total time taken by now is 3 min.

**Time left before the bridge collapsed = 14 mins**

C & D crosses the bridge in 10 mins and B returns with the torch in 2 mins, so the total time taken by now is 15 min.

**Time left before the bridge collapsed = 2 mins**

Now, A & B were only left out and the time left before the bridge collapsed in 2 min but the maximum time taken by A & B to cross the bridge is 2 mins as the time taken by A is 1 min and by B is 2 mins.

**Hence A, B, C, and D four will cross the bridge within 17 mins.**

### Prime Course Trailer

### Related Banners

Get PrepInsta Prime & get Access to all 200+ courses offered by PrepInsta in One Subscription

**Get over 200+ course One Subscription**

Courses like AI/ML, Cloud Computing, Ethical Hacking, C, C++, Java, Python, DSA (All Languages), Competitive Coding (All Languages), TCS, Infosys, Wipro, Amazon, DBMS, SQL and others

**Death & Marbles Puzzle Answer****Airplane Seat Puzzle Answer****2 Eggs & 100 Floors Puzzle Answer****Bank Cashier Puzzle Answer****Calendar Cube Puzzle Answer****Ants & Triangle Puzzle Answer****Measuring 9 mins Puzzle Answer****Bulb in a Circle Puzzle Answer****Camel & Bananas Puzzle Answer****King & Wine Puzzle Answer****Sum & Product Puzzle Answer****Heaven or Hell Puzzle Answer****3 Mislablled Jars Puzzle Answer**

Login/Signup to comment