You see a boat filled with people, yet there isn’t a single person on board. How is that possible?

What number does the below three word/phrase identify and why?
1. Deck
2. Year
3. Singing in the Rain

I am thinking of a five-digit number such that:
The first and last digits are the same, their submission is an even number and multiplication is an odd number and is equal to the fourth number. Subtract five from it and we obtain the second number. Then divide into exact halves and we get the 3rd number.

What number I am thinking of?

John and Jill are madly in love with each other. To remind Jill of his pure love, John wants to send her a ring by post but in their country where burglary is quite prominent, any package that is not locked comes under the risk of being stolen for the contents.

John and Jill possess many padlocks but neither one of them has the other key.

Can you find a way John can send the ring to Jill safely?

A brand new Mobile Phone was on sale at 20% as a promotional offer. By what per cent must the Mobile price be increased to sell it at the original price again?

Different lights make me strange by changing me into different sizes. What am I?

Can you decipher the following common phrase?

T M C
A U O
H S M
W T E

If we add four times the age of John four years from now to five times his age five years from now we get ten times his current age.

How old will John be two years from now?

What Adam and Eve do not have but the rest of the people have?

What has a ring but no finger?