Amazon Interview Question Half the cable length is 40 feet, so the cable must be hanging straight down, i.e. the poles are touching.
Live Another Day The outcome of the two tosses will either be the same or different, so they decided on a simple strategy: Tulip will always predict the same (e.g. she sees a head and predicts Jesse will see a head) while Jesse will always say the opposite (e.g. he sees a head and guesses Tulip saw a tail). One of their guesses will always be correct.
Go for the Girls! It's 50/50, since each baby born is as equally likely to be a boy as a girl, no matter what the king says.
More Girls 1 in 3. She might have (in birth order) girl-girl, girl-boy or boy-girl. Only one of these three options results in her other child being a girl.
Triangles There are 18 triangles.
Timepieces Sundial; hourglass.
Letters ITS (In The Sequence).
Dormitory Dirty room.
Roman Numerals Turn it upside down.
1876 MIT Entrance Exam They are 50 and 18. (Two years ago, they were 48 and 16; in 14 years, they will be 64 and 32.)
Sum S = 1 + 1/2 + 1/4 + 1/8 ...; S/2 = 1/2 + 1/4 + 1/8 ...; subtract, canceling out everything except the 1, giving you S – S/2 = 1, QED.