A mother randomly selected two of her children to pick up a package from the post office. There was a 50% chance both children were daughters. How many daughters does this mother most likely have?
Difficulty – Medium
Medium difficulty brain teasers and puzzles
Rebus Puzzle 16
What common word or phrase is this rebus referring to?
SIXTEEN
THOUSAND
FIFTY
NINE
TRILLION
THIRTYSolution
Safety in numbers
(“Safety” is spelled out downwards in the numbers listed.)
Hidden Word
What hidden word can be found among these pairs of words?
- Staple, paste
- Phasor, sharp
- Uneven, venue
- Secret, crest
- Litter, title
First to 100
You and a friend play “first to 100”, a game in which you start with 0, and you each take turns adding an integer between 1 and 10 to the sum. Whoever makes the sum reach 100 is the winner.
Is there a winning strategy? If so, what is it?
Blue and Red Maze
In this maze, you must alternate going through blue and red doors – in other words, you cannot go through two blue doors in a row or two red doors in a row.
Entering through the blue door in the top left, can you find your way through the maze and exit through the red door in the top right?
Rebus Puzzle 14
What common word or phrase is this rebus referring to?
serGeant
geNeral
ensIgn
priVate
colOnel
adMiralSolution
Moving up the ranks
(Each line is a rank in the military, and “moving” is spelled upwards among the ranks.)
3 Digit Code
You have six guesses to figure out a 3 digit code. After each guess, you will be told exactly how many digits are correct but in the wrong place and how many digits are correct and in the right place. You have made these five guesses already:
- 865: exactly one digit in the right place
- 964: exactly one correct digit but in the wrong place
- 983: no correct digits
- 548: exactly two correct digits but in the wrong places
- 812: exactly one correct digit but in the wrong place
What is the correct 3 digit code?
Tennis in 2 or 3 sets
In a best of 3 tennis match, the player that first wins 2 sets wins the match. For a 3-set tennis match, would you bet on it finishing in 2 or 3 sets?
This question was asked in an actual D. E. Shaw quant trading interview.
Preparing for a brain teaser interview? Check out our ultimate guide to brain teaser interviews.
Guess the Number
Jake has a 4-digit number in mind and asks Raj to guess the number. Raj can have 7 guesses, and Jake will give him some hints after 6 guesses.
Raj makes these 6 guesses:
- 6 3 5 8
- 9 3 0 6
- 4 8 8 2
- 6 7 2 8
- 1 1 9 1
- 5 6 2 7
These were all wrong, but Jake says every guess had exactly one (and only one) correct digit in the correct position. Additionally, all the digits are different.
What should Raj’s 7th guess be?
Chess Knight Assassin
From its starting position, the white knight that captured the black queen has moved exactly eight times to get where it is now. How is this possible?
