Cristina was born in 1888. She just had her 30th birthday today how did that happen?

In particular commonwealth games, a female participant won silver and gold medals for a single event.

How can this be possible?

I have nine bottles of wine and one of the nine bottles is poisoned.
I need to find the poisoned bottle with two facts
(1) Poison is deadly, only a sip will cost death
(2) I have two mice to do so.

How should I do it?

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

Which is the smallest number that you can write using all the vowels exactly once?

I have four wings but can't fly.
I express no emotions.
I am found on the exact spot every time you look.
I keep toiling away with a little sound.

Do you know what am I?

Why is the Hole below a Lock?

What 5-letter word typed in all capital letters can be read the same upside down?

John was driving a bus and got stuck when passing through an underpass. Then came Jacob with a needle and got the bus out of the underpass.

What did the boy do?

For an extra income, John decided to work at a Hotel for one hour daily. The manager offers him that they will pay him $11 after every 11 days.
However, John offered a different proposition to the manager. The offers stand as:
He will be paid just a penny on his first day.
Two pence will be paid on the second day,
Four pence will be paid on the third day.
And so on till the 11th day.

Should the Hotel manager accept his offer?