What is the fastest way to double your money?

Can you spot the man between the coffee bean in the picture below ?

Two trains start at the same time, one from Bangalore to Mysore and the other from Mysore to Bangalore. if they arrive at their destinations one hour and four hours respectively after passing one another, how much faster is one train running than the other?

Two fathers and two sons went fishing one day. They were there the whole day and only caught 3 fish. One father said, that is enough for all of us, we will have one each. How can this be possible?

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

What Am I?

I am Huge on Sunday and Saturday.
I am small from Tuesday to Thursday.
I do not exist on Monday and Friday.
Who am I?

Can you decipher the below rebus?

PBLUESAISNUERSES

Can you replace the question mark with the correct letter?

6 + 6 + 6 = N
7 + 7 + 7 = E
8 + 8 + 8 = R
0 + 0 + 0 = ?

What is the largest amount of money that you can possess in change and still if someone asks you for a dollar, you won't be able to give?

They do not possess flesh or feathers or scales or bone
But still, they are blessed with fingers and thumbs of their own.