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:

7

Explanation:
8th is bald man head, check the video below.

Solution:

It can be done in 8 moves as shown in the animated image below.

Solution:

fIvE thOUsAnd(5000)

Solution:

See the colored sticks in the picture. We have moved those sticks in the position given in the second image corresponding with the color.

Solution:

457730 * 4 = 1830920
(DOLLAR * 4 = QUARTER)

Solution:

The probability of two numbers being relatively prime is 60%. Thus if you keep playing the bet, you will hypothetically make 20 cents on every play.

Thus, you should accept the bet.

Solution:

Set the first switches on for abt 10min, and then switch on the second switch and then enter the room.
Three cases are possible
1.Bulb is on => second switch is the ans
2.Bulb is off and on touching bulb , you will find bulb to be warm
=>1st switch is the ans.
3.Bulb is off and on touching second bulb , you will find bulb to be normal(not warm)
=>3rd bulb is the ans.

Solution:

Move and then pour all juice from second glass to fifth glass.

Solution:

Never

Explanation:
In the question, the distance of x miles is given at a particular moment. The middle car is running at that time at 50 MPH. The distance will keep increasing with time as three are running at different speeds. It will increase by x miles every hour till a certain point of time and then it will start decreasing till the fastest car meets the slowest again.

As per question, all the cars stop then. Thus, the distance will never be x miles again.

Solution:

Hockey Stick $49.50 & ball $0.50