River Crossing with one Torch

Four people need to cross a rickety bridge at night. Unfortunately, they have only one torch and the bridge is too dangerous to cross without one. The bridge is only strong enough to support two people at a time. Not all people take the same time to cross the bridge. Times for each person: 1 min, 2 mins, 7 mins and 10 mins. What is the shortest time needed for all four of them to cross the bridge?

River Crossing with one Torch




Similar Riddles

A rain drop fell from one leaf to another leaf and lost 1/4th of its volume. It then fell to another leaf and lost 1/5th of the volume. It again fell on another leaf and lost 1/5th of the volume.



This process kept repeating till it fell on the last leaf losing 1/75th of its volume.



Can you calculate the total percentage of loss from the initial volume when the drop has fallen to the last leaf accurate up to two decimal places?

Asked by Neha on 16 Feb 2021


John replied, when asked how old he was. In 2 years he will be twice as old as he was five years ago.' How old is he ?

Find the age

Asked by Neha on 10 Apr 2021

You have two rectangular wires.

Both of them have property that when you light the fire from one end , it will take 60 minutes to get completely burn.

However, they do not burn at consistent speed (i.e it might be possible 1st 20% burn in 50 minutes and 80% can burn in 10 minutes).

So how could you measure 45 minutes ?

Asked by Neha on 21 Feb 2021


What you cannot hold but it is yours?

Asked by Neha on 28 Dec 2024

The following four words might seem abrupt to you. But you can make them meaningful by just adding vowels.
RDSH
GGPLNT
TMT
NN

Hint: All of them are vegetables.

Asked by Neha on 13 Nov 2025

Below, you can see some coding:
January = 1017
February = 628
March = 1335
April = 145
May = 1353
June = 1064
July = 1074
August = 186

Now deciphering the way it has been coded, can you find out how September will be coded?

Asked by Neha on 30 Jan 2025


If,

6 / 7 = 2
3 / 9 = 7
8 / 2 = 6

Then

4 / 5 = ?

Asked by Neha on 15 Apr 2025

Replace the letters of words with a number so that the below equation holds true

BASE +
BALL
---------
GAMES
----------

Asked by Neha on 10 Oct 2023

1. What does:
TIM JOB
represent?

2. What does:
MO_ _
represent?

Asked by Neha on 21 Feb 2025


Find the next number in the series?
2, 12, 36, 80, 150, 252, 392, _ ?

Asked by Neha on 22 Jan 2024

Hot Articles

Amazing Facts

Gambling

In Canada, a mathematical puzzle must be solved in order to win the lottery to classify it as a “game of skill” not gambling.