Aplusclick Best Puzzles 2019

These are the Best Puzzles published at www.aplusclick.org in 2019.

 

Aplusclick Best Puzzles 2019 from Igor Kokcharov, Ph.D, PMP

JUICE, SODA, and LUCKY

A drinks dispenser has three labelled buttons: JUICE, SODA, and LUCKY. If you press LUCKY you are supposed to get either juice or soda with equal probability.

Each button is wired to exactly one of these functions, but each function is not necessarily wired to exactly one button.

Assuming that you are clever, but unlucky, how many button presses are required to establish exactly which button does which function?

 

Check the answer

Back to School – Friendship Math

It is the first day of a new school year, and this class has only 10 students.  Ashley has 9 friends, Betty has 8, Caleb has 7, Derek has 6, Elaine has 5, Graham has 4, Henri has 3, Ivana has 2, Julie has 1.  Name one of Fred’s friends.

Answer

In a group of 4 school children, each child has exactly two friends, just one of which is their best friend. What is the minimum possible number of children for whom their best friend is also that friend’s best friend?

Answer

 

It is the first day of a new school year, and this class has only 10 students.  Ashley has 9 friends, Betty has 8, Caleb has 7, Derek has 6, Elaine has 5, Graham has 4, Henri has 3, Ivana has 2, Julie has 1.  How many friends does Fred have?

Answer

It is the first day of a new school year, and this class has only 5 students. Amy has no friends yet. Betty has one friend. Chris has three friends. Derek has two friends.  How many friends does Ellie have?

Answer

In a group of five students, Ann has one real friend among them, Betty has two,  Craig has three, and Dianna has two. How many real friends does Edgar have in the group?

Answer

Motorway Problem

How to choose the shortest road that connects several towns. This is a story about local and global minimums. Excellent presentation  of soapy films.

Unrepresentative Voting

Leslie Green explains how our voting systems can be unrepresentative.

Five different parties are standing in an election for one representative. The voting  methods:  First past the post (FPTP): the party with the highest vote-count wins.

Is the voting system representative?

The no-pets party has 30% of the total, whereas parties that want pets are the remaining 70%.  As it stands the FPTP system would vote-in the no-pets party, which does not represent the view of the electorate.  What has happened is that the pro-pet movement has splintered, dividing the vote. In order to overcome this, one can use a transferable vote scheme so people can vote for their preferred option safely, preventing the hated no-pets party from winning.

A more detailed analysis can be found in an example.

First Woman to Win the Abel Prize

Karen Uhlenbeck to win the most prestigious award in mathematics – the Abel Prize.

The Norwegian Academy of Science and Letters has decided to award the Abel Prize for 2019 to Karen Keskulla Uhlenbeck of the University of Texas at Austin, USA.

Her theories have revolutionized our understanding of minimal surfaces, such as those formed by soap bubbles.

Niels Henrik Abel (1802–1829) was a Norwegian mathematician. In spite of his short life, he made significant contributions to a variety of mathematical fields.

Creativity is the Key Skill of the Future

According to Jack Ma:

The key feature skills of the Future are:

– Value
– Believing
– Independent thinking
– Team work
– Care of others

In the future, it is not about a competition of knowledge, it is a competition of creativity, it is a competition of imagination, it is a competition of learning.