Solution:

The total population of New York City is about nine millions. Let us assume that 1 million among them are bald which leaves us with eight millions of people that are required to have different number of hairs on their head.

Now as per the surveys, on an average, people have 100, 000 hairs on their head. Since all must have different numbers, we start with one. Let us say someone has one hair strand, someone has two, and someone has three and so on. After 100, 000 people, we are left with 7, 900, 000 people left. Since all of them are needed to have different number of hair strands, we will move up from 100, 000.

In such case, at the end, you will be having a person with 8, 000, 000 hairs which is clearly impossible (even having 1, 000, 000 hairs on someone's head is impossible).

Therefore, there must be two people who have same number of hairs on their head.

This is a classic example of the pigeonhole principle.

Solution:

A cone consists of just two surfaces.

Solution:

The worth of that coin is zero. This is because the B.C. and A.D. dating system was not empowered till the year 525. So the coin is probably fake.

Solution:

It is at the North Pole.

The winds are blowing towards the north till they reach the pole. The moment the pole is crossed, they are blowing towards south.

Solution:

They used square manhole covers in Baker Street. As the side is smaller than the diagonal of the square, they were prone to fall when twisted. However the manhole covers were round shaped in Crawford Street making them impossible to fall inside.

Solution:

125874 => 251748

251748 is twice the 125874 and have same digits 1,2,4,5,7 & 8

Solution:

2024

Seven occurrence
24-01-24
12-02-24
08-03-24
06-04-24
04-06-24
03-08-24
02-12-24

Solution:

44

In 12 hours, the minute and hour hands overlaps or are in exact opposite direction 22 times.
=> In 24 hours, the hands overlaps or are in opposite direction 44 times

Solution:

The doors at 'The Coconut Grove' opened inward. In the mad panic to escape the fire, people were crushed against the doors and could not pull them open. After 'The Coconut Grove' disaster in 1942, all public buildings had to have doors which opened outward.

Solution:

He fell into the Dead Sea, which lies between Israel and Jordan. The water is so salty and dense that anyone in it floats very easily.