Q1 can't have A as its answer (otherwise it would contradict itself).
If Q1's answer was C (meaning Q4's answer was A), then Q3's answer would be C. However, Q2's answer should now be A, but this isn't allowed by Q1 (as Q4 is the first answer with A). This is a contradiction.
Therefore Q1's answer is B (meaning Q3's answer is A).
For Q2's answer to be C, Q4's answer would have to be A, which would contradict Q4. Therefore Q2's answer is B, making Q4's answer B. QED.
What 5 digit number am I thinking of.
It has two prime digits.
Digit 3 is the highest digit.
Digit 2 is lowest digit.
Digit 1 is higher than the sum of digits 4 and 5.
Digit 5 is half of digit 4.
Digit 1 is one smaller than digit 3.
Digit 5 is between digit 2 and digit 1
There are no duplicates and the digit 0 doesn't appear.
Since digit 5 is half of digit 4 we have four possibilities:
_ _ _ 2 1
_ _ _ 4 2
_ _ _ 6 3
_ _ _ 8 4
But since digit 1 is higher than the sum of digit 4 and digit 5 we can eliminate two possibilities leaving:
_ _ _ 2 1
_ _ _ 4 2
Since digit 5 is between digit 2 and digit 1, we can eliminate _ _ _ 2 1, leaving:
_ _ _ 4 2
Since digit 1 must be higher than the sum of digit 4 and digit 5 we have three possibilities:
7 _ _ 4 2
8 _ _ 4 2
9 _ _ 4 2
But digit 1 is 1 smaller than digit 3 we can eliminate 9 _ _ 4 2, leaving
7 _ 8 4 2
8 _ 9 4 2
Since digit 2 is the lowest number, it must be 1:
7 1 8 4 2
8 1 9 4 2
The answer has exactly 2 prime digits, which only leaves
7 1 8 4 2. QED.
You find yourself playing a game with your friend.
It is played with a deck of only 16 cards, divided into 4 suits:
Red, Blue, Orange and Green.
There are four cards in each suit:
Ace, King, Queen and Jack.
Ace outranks King, which outranks Queen, which outranks Jack - except for the Green Jack, which outranks every other card.
If two cards have the same face value, then Red outranks Blue, which outranks Orange, which outranks Green, again except for the Green Jack, which outranks everything.
Here's how the game is played: you are dealt one card face up, and your friend is dealt one card face down. Your friend then makes some true statements, and you have to work out who has the higher card, you or your friend. It's that simple!
You are dealt the Red Queen and your friend makes three statements:
1. My card could lose to a Blue card.
2. Knowing this, if I am more likely to have an Ace or a King than a Queen or a Jack, then I have an Orange card. Otherwise, I don't.
3. Given all of the information you now know, if I am more likely to have a Jack than an Ace, then I actually have a King. Otherwise, I don't.
Hint: These are the first letters of the words: T, T, H, D, W, L, H, W, C, N
TEL + ESC + OPE = TELESCOPE
TIM + ETA + BLE = TIMETABLE
HAI + RBR + USH = HAIRBRUSH
DIF + FER + ENT = DIFFERENT
WAT + ERF + ALL = WATERFALL
LIG + HTN + ING = LIGHTNING
HEA + DLI + GHT = HEADLIGHT
WHI + RLW + IND = WHIRLWIND
CAR + TIL + AGE = CARTILAGE
NEW + SAG + ENT = NEWSAGENT