If in ten hours, the container is filled completely then how long would it have taken to be filled half?

Question

A large container is kept in open under the rain. Every passing hour, the water collected inside the container becomes double it was.
In ten hours, the container is filled completely. Can you calculate how long would it have taken to be filled half?

Answer 1

If the water doubles every hour, the container was half full in 9 hours.
The next hour would fill it completely.

Answer 2

As it requires only 1 hour to double the quantity, 9hour will require to fill it half.