If it took eight men ten hours to build a wall, how long would it take four men to build it?

Find the next number in the series

12, 20, 40, 72, 116, 172 ?

We have four gears with below features=> Both Gear A and D has 60 teeth=> Gear B has 40 teeth=> Gear C has 20 teeth=> Every two minutes, Gear B makes 25 full turns.What is the relative speed of Gear A and Gear B?

What has many keys but can’t open a single lock?

You have a three-gallon and a five-gallon measuring device. You wish to measure out four gallons.

"That Restaurant always remains crowded. This is the reason why nobody goes there".

Can you find a flaw in this statement?

Which of the below owl is odd one out?

Accidentally, two trains are running in the opposite direction and enter a tunnel that is 200 miles long. A supersonic bird that has fled the lab and taken shelter in the tunnel starts flying from one train towards the other at a speed of 1000 mph. As soon as it reaches the second train, he starts flying back to avoid collision and meets the first train again at the other end. The bird keeps flying to and fro till the trains collide with each other.

What is the total distance that the supersonic bird has traveled till the trains collided?

If,

A + B = C
D - C = A
E - B = C

Based on the above equations, find out the answer for:

D + F = ?

I have holes on the top and bottom. I have holes on my left and on my right. And I have holes in the middle, yet I still hold water. What am I?