What do you call a fish without an eye?

Find the missing letter in the last circle logically in the given below picture.

You walk into a room that contains a match, a kerosene lamp, a candle and a fireplace. What would you light first?

I am lying and I always lie. Tell me whether I am lying or telling the truth.

In a school, there are four subjects. Seventy percent of students study English, seventy five percent of students study Science, eighty five percent of students study Mathematics and eighty percent of students study Spanish.

Can you calculate the percentage of students that study all four subjects?

Twice ten are six of us,

Six are but three of us,

Nine are but four of us;

What can we possibly be?

Would you know more of us?

Twelve are but six of us,

Five are but four, do you see?

What are we?

Why is it very easy to weigh a fish?

Can you find the ages of a son, father and grandfather based on the following facts?
The sum of the ages of grandfather, father and son is 140 years.
The age of the son in months is the same as the grandfather in years.
The age of the son in days is the same as the father in weeks.

All of the flowers I have are orchids except two. All of the flowers I have are hibiscuses except two. All of the flowers I have are roses except two.

Can you tell me how many flowers I have?

I am taken from a mine and shut up in a wooden case, from which I am never released, and yet I am used by almost every person. What am I?