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

Can you replace the question mark with the correct number in the below table sequence?

An American nightclub called 'The Coconut Grove' had a terrible fire in which over 400 people died. A simple design flaw in the building led to a high death toll. Subsequently, regulations were changed to ensure that all public buildings throughout the country eliminated this one detail, which proved deadly. What was it?

Different lights make me strange by changing me into different sizes. What am I?

If you go to the movies and you're paying, is it cheaper to take one friend to the movies twice, or two friends to the movies at the same time?

The answer I give is yes, but what I mean is no. What was the question?

A man has a barrel filled with oil that weighs 100 pounds, and then he puts something into it. Now the barrel weighs less than 100 pounds. What did he put in the barrel?

John left on a horse on Thursday , was gone for two days, and came back on Thursday after completing his work. How did that happen?

Solve the counting riddle by identifying the number of triangles in the given picture.

Do you know who was buried in John's tomb?