The Prime Number Riddle
Two hundred people in an auditorium are asked to think of a single digit number from 1 to 9 inclusive and write it down. All those who wrote down a prime number are now asked to leave. Ninety people remain behind in the hall. How many of these are expected to have written down an odd number?
Hint: Remember that 1 is not a prime number.
Those that remain behind must have written {1,4,6,8,9} and from this only {1,9} are odd. The probability of an odd number is thus 2/5.
Expected number of odds is 2/5 * 90 = 36 Did you answer this riddle correctly?
YES NO
Expected number of odds is 2/5 * 90 = 36 Did you answer this riddle correctly?
YES NO
Positive Numbers
Hint:
A Nose That Grows
Every time a man lies his nose grows to 150 percent of its size. Every time he tells the truth it shrinks to 50 percent of its size.
What will happen if he alternates between lies and the truth
What will happen if he alternates between lies and the truth
Hint:
For every pair of a truth and a lie his nose will shrink to 75 percent of its previous size prior to this truth and lie. So the correct answer is 0. As the number of times he tells a lie and the truth ((3/4)n) approaches infinity the length of his nose approaches 0. Did you answer this riddle correctly?
YES NO
YES NO
A Doctor And Nurse
A doctor and a nurse have a baby boy. But the boy's father is not the doctor and the mother is not the nurse. How is this possible?
Hint:
The doctor is the mother (female doctor) and the nurse is the father (male nurse). Did you answer this riddle correctly?
YES NO
YES NO
September October November Riddle
In September, you pick me when I'm good and ready.
In October, you cut me intentionally to make me look worse.
In November, you trash me like you never knew me.
What am I?
In October, you cut me intentionally to make me look worse.
In November, you trash me like you never knew me.
What am I?
Hint: It helps if you think about each month differently and then as a whole.
One Odd Number
Hint:
What Is Brown And Sticky
Hint:
The Tired Nose Riddle
Hint:
Cows Night Out
Hint:
Only Self-Enumerating Number
Hint:
Four. The number four has four letters, making it self-enumerating. Did you answer this riddle correctly?
YES NO
YES NO
An Odd Number Made Even Riddle
Hint:
Even Number Riddle
Hint:
Cents In A Nickel Riddle
Hint:
The Even Number Riddle
Hint:
Not An Even Number Riddle
Hint:
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