Can you place six X (crosses) in below board without making three in a row in any way ?

Solve the equation in the image by looking at the pattern closely.

If an electric train is travelling south, then which way is the smoke going?

Begin with a word, five letters to my name,
Remove the first and last but I am the same
Take out my middle and still, I remain.
What word am I?

A mathematics teacher took exams for his students. Out of the total students, 25% passed both the tests included in the exam. However, only 42% were able to clear the first test.

Can you find out the percentage of those students who passed the first test and also passed the second test?

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?

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

By using 'because' continuously three times, can you make an English statement ?

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?

There was an aeroplane crash, every single person died, but two people survived. How is this possible?