I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

Can you find a pattern and the missing number in the series given below?

100, 155, 258,? , 584, 819.

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

ENEMY = 2 * LINK
LINK + 2 = HELL

Then what will be TAXI + HELL? Select from the options below:
a) ROTTEN
b) DANGER
c) HEAVEN
4) MORTAL

A train full of passengers goes through a tunnel. When the train comes out from the other end, there is no single person on the train.

How did it happen?

We have shown you a regular water barrel as below. Without using any measuring device can you check if the barrel is more than half-filled or less than half-filled?

When it's bad luck to meet a black cat?

There is something which you can be arrested for attempting but not for successfully completing.

Keyboard words are not in alphabetical order, Why?

If 2 workers can complete painting 2 walls in exactly 2 hours.

How many workers would be needed to paint 18 walls in 6 hours?