What is the Surname of Barbie Doll?

A mile-long train is moving at sixty miles an hour when it reaches a mile-long tunnel. How long does it take the entire train to pass through the tunnel?

You are in a room that has three switches and a closed door. The switches control three light bulbs on the other side of the door. Once you open the door, you may never touch the switches again. How can you definitively tell which switch is connected to each of the light bulbs?

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?

What is full of holes but still holds water?

Why is the Hole below a Lock?

Can you find out the remainder when 3^300 is divided by 5?

John went to a parrot shop in Mexico, and the parrot owner told him that his parrot is so unique that he repeats everything he hears. John got excited and immediately bought the parrot. John went home and spoke many words, but the parrot does not repeat anything.
He went again to the parrot shop and complaint to the shopkeeper, but the shopkeeper never lied. Explain?

81 x 9 = 801. What must you do to make the this equation true?

Who always enjoys poor health?