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

Four friends are sitting on a tree. Each one of them is wearing a hat. They don't know which coloured hat are they wearing but they do know that two of them have green hats and two of them have orange hats.

Adam is sitting on the top branch and he can see the hats of Billy and Cyrus. Billy is sitting on a branch above Cyrus and he can see Cyrus hat. Duke is sitting at the base of the tree. Branches are covering him fully and no one can see his hat.

Now they are not allowed to look upwards. Who do you think will shout the colour of his hat first?

Outside a massage parlour, there is a board that reads
"I only massage those who do not massage themselves."

Reading the above statement, does the masseur massage himself?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

Can you find out the number that should replace the question mark with a valid reason?

What does this rebus means ?

PROG WORKRESS

A bomb exploded in a room full of married couples and no one died. How?

One is to three as three is to five and five is to four and four is the magic number.
What is the pattern?

I am the black child of a white father, a wingless bird, flying even to the clouds of heaven. I give birth to tears of mourning in pupils that meet me, even though there is no cause for grief, and at once on my birth, I am dissolved into air. What am I?

Can you find the six hidden animals in the picture below?