Answer – 0.1 liters of water

Explanation-
Mark has 0.96/2 liters of pure alcohol i.e. 0.48L
To get 80%,
he needs 0.96/2/0.8=0.6 total liters of fluid.

He already has 1/2 a liter of fluid, so he needs 0.6-0.5=0.1 liters of water to get there.

Answer- Pay 7 Coins to the first person and 1 coin to the second

Explanation-
If the passenger pays 8 coins for his share of the meal, then
The whole amount of food consumed is worth 24 coins, and thus each slice of bread is worth 3 coins.

The first man      – provides 5 slices of bread, worth 15 coins, and eats 8 coins’ worth, so he should be paid 7 coins.
The second man –  provides 3 slices of bread, worth 9 coins, and eats 8 coins’ worth, so he should be paid 1 coin.

This is a classic example of the pigeonhole principle.

The argument goes as follows:
Assume that every non-bald person in New York City has a different number of hairs on their head. Since there are about 9 million people living in NYC, let’s say 8 million of them aren’t bald.

So, 8 million people need to have different numbers of hairs on their head. But on average, people only have about 100,000 hairs. So even if there was someone with 1 hair, someone with 2 hairs, someone with 3 hairs, and so on, all the way up to someone with 100,000 hairs, there are still 7,900,000 other people who all need different numbers of hairs on their heads, and furthermore, who all need MORE than 100,000 hairs on their head.

You can see that additionally, at least one person would need to have at least 8,000,000 hairs on their head, because there’s no way to have 8,000,000 people all have different numbers of hairs between 1 and 7,999,999. But someone having 8,000,000 is an essential impossibility (as is even having 1,000,000 hairs), So there’s no way this situation could be the case, where everyone has a different number of hairs. Which means that at least two people have the same number of hairs.

Algorithm-

[Label: move_slowly]
1 Move Right
2 Move Right
3 Move Left
4 Skip Next Instruction If On Oil
5 GOTO move_slowly

[Label: move_quickly]
6 Move Right
7 GOTO move_quickly

Answer – Tisha

Explanation:
Lady Gaga is a singer and so loves musical notes. The first two letters of each name form the musical notes

Dorry Rebeka Michael Faniya Sophia Lavanya
The musical notes are
Do Re Mi Fa So La __

Next sequence of musical notes is “Ti” and only name started with Ti is “Tisha”

Answer – The Bathtub

Explanation-
The more you shower inside a bathtub, the more dirtier it becomes.

Wind

Move disk 1 from rod A to rod B
Move disk 2 from rod A to rod C
Move disk 1 from rod B to rod C
Move disk 3 from rod A to rod B
Move disk 1 from rod C to rod A
Move disk 2 from rod C to rod B
Move disk 1 from rod A to rod B
Move disk 4 from rod A to rod C
Move disk 1 from rod B to rod C
Move disk 2 from rod B to rod A
Move disk 1 from rod C to rod A
Move disk 3 from rod B to rod C
Move disk 1 from rod A to rod B
Move disk 2 from rod A to rod C
Move disk 1 from rod B to rod C

Solution Steps –
Disk 1 moved from A to C
Disk 2 moved from A to B
Disk 1 moved from C to B
Disk 3 moved from A to C
Disk 1 moved from B to A
Disk 2 moved from B to C
Disk 1 moved from A to C

The vet could see that the goldfish was dying of old age so to spare the old lady’s feelings he dashed out and bought a young but identical fish and disposed of the old one.

Explanation-
Points to be noted are-
1) Did the vet change the water? – No!
2) Did he give the fish any medication, food, or tonic? – No.
3) Had the woman had the goldfish for a long time? – Yes.