#301 - Prime Number Maths Puzzle

How many prime numbers less than 100 are there that when divided by 5 leaves an odd remainder?

13 numbers

Since we are looking to find odd reminder which implies that the remainder will be either 1 or 3
Therefore number must follow below two conditions:
A) We can list number 5n + 1 or 5n + 3. (where n = 0,1,2,3.....)
B) The number must end in 1 or 3.

List of such numbers less than 100 are:
1, 3, 11, 13, 21, 23, 31, 33, 41, 43, 51, 53, 61, 63, 71, 73, 81, 83, 91, 93

Let us remove the nonprime ones which are 1, 21, 33, 51, 63, 81 and 91

So, I will be left with 13 numbers which fit the bill.
3, 11, 13, 23, 31, 41, 43, 53, 61, 71, 73, 83 and 93

#302 - Matchsticks Relationship Riddle

What is the relationship between these matchsticks pictures below?

Matchsticks Relationship Riddle

Remove the same 2 matchsticks from each figure and move figure towards left 45 degrees, It forms the letters V W X Y.

#303 - Tricky Girl Child Probability Puzzle

In New York Park area, there are two Houses H1 and H2. Both H1 and H2 have two children each.
In House H1, The boy plays for New York Youth academy and the other child plays baseball.
In House H2, The boy Plays soccer for his school at New York and they recently have a newborn.

Can you prove that probability of House-H1 having girl child is more than that of House-H2?


In House H2, we know that older child is boy, therefore there are two cases
Older Younger
Boy Girl
Boy Boy
Probability of at least one girl child: 1/2

In House H1 there are three cases
Older Younger
Boy Girl
Boy Boy
Girl Boy
Probability of at least one girl child: 2/3

#304 - Missing Year Sequence Puzzle

Can you find the missing year in the number sequence below?

1997 1999 2003 2011 ? 2027

2017 (It is a series of prime numbers)

#305 - Yesterday Tomorrow Puzzle

John said, "If yesterday was tomorrow, today would be Friday."

When did John make this statement?

Wednesday

There is two way to interpret this.
A) If z + 1 ==> z - 1
Then
z ==> z - 2
z - 2 = Friday
z = Sunday

B)If z - 1 ==> z + 1
Then
z ==> z + 2
z + 2 = Friday
z = Wednesday

Option B) makes sense and hence the answer.

#306 - Real Name Puzzle

My friends called me Iron59 because my parents are a chemist and a mathematician.What is my real name?

Felix
Iron = Fe (chemical symbol)
59 = LIX (Roman numerals)

#307 - Maths Symbol Decipher Rebus

A maths symbol is hidden in the below rebus. Can you decipher it?

Maths Symbol Decipher Rebus

Pie

This is the bar graph that represents the number (3, 1, 4, 1, 5, 9, 2, 6, 5) .
and we know the value of pie is 3.14159265

#308 - Maze Riddle

You need to complete the maze by entering from the entrance (near yellow circle - bottom left) and they leave from the exit point (near green circle - bottom middle).You need to follow below rules: 1. You can go through one circle more than once. 2. You can move only by exchanging green and yellow circles.

Maze Riddle

It can be solved as below

#309 - Classic Philosophical Betrayed Riddle

John and Sophie were so frustrated with their life that they decided to end the misery by ending their life. They decided that both will jump off the building on the count of three. They started counting and on the count of three, John jumped white Sophie did not. She watched John fall off for around seven seconds when the parachute opens.

Who betrayed whom?

John betrayed Sophie.
Sophie may not jump because of the survival instinct and therefore can be given a benefit of the doubt, whereas John having the parachute seem a well-thought plan.

#310 - Cipher Matchsticks Riddle

Can you decipher the two rows to find the hidden word?

Cipher Matchsticks Riddle

Flip the two rows 1 and 2 vertically, you will find the word "Lotto".