What is the fastest way to double your money?

There are five vowels (a, e, i, o, u) in the English language.
Can you tell us a word that contains all these vowels?

What does this rebus means ?

They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

What Does this text mean:

important=important

The average age of 10 members of a committee is the same as it was 4 years ago, because an old member has been replaced by a young member. Find how much younger is the new member ?

I am a white box having no key or lid.
Yet there is a golden treasure inside it.

What Am I?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

Can you name four days which start with the letter 'T'?

I have cities, but no houses. I have mountains, but no trees. I have water, but no fish. What am I?