150 Puzzles to Challenge Your Mental Skills

Author: Pierre Belokan
Publisher:
Publish Date: 2006-08-01
Features:
Problem 1: The Desert Journey ahead is a desert. Your task is to plant a flag in the desert and then return. It will take 4 days to walk from here to the spot where you plant the flag. You have no special equipment and must rely on your own strength, but you can recruit one or more companions to help. Carrying food and the flag is no problem. The only limitation is regarding water: each person can carry only enough water for one person to drink for 5 days. Therefore, if you go alone, the water you can carry is only enough for you to walk towards your destination for 2.5 days and then return to the starting point. Besides these conditions, if you are also limited to recruiting at most 3 companions and carrying at most enough water for one person to drink for 20 days, how can you complete this task?
Problem 2: Pure Reasoning In the early 20th century, the concepts of "group" and "relation" were far from popular, and algebra itself was not widely accepted in education. People still had some doubts about the teaching value of algebra. Logical arguments were considered more important than unknowns and equations. Here, we have an opportunity to return to that era and experience the power of "pure reasoning" once again. A train takes 7 seconds to pass by a stationary observer and 26 seconds to completely pass through a 380-meter-long station. What is the speed of the train? How long is it?
Problem 3: Digits and Age Let's keep it "pure." As in Problem 2, you are not allowed to use unknowns or equations. If a person's age in 1898 is the sum of the digits of their birth year, what is that age? P1