If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

Count the number of times the letter "F" appears in the following paragraph:

FAY FRIED FIFTY POUNDS OF
SALTED FISH AND THREE POUNDS
OF DRY FENNEL FOR DINNER FOR
FORTY MEMBERS OF HER FATHER'S FAMILY.

How can you make the following equation true by drawing only one straight line: 5+5+5=550 ?

I’m tall when I’m young, and I’m short when I’m old. What am I?

What has many keys but can’t open a single lock?

What is the Surname of Barbie Doll?

If you were to put a coin into an empty bottle and then insert a cork into the neck, how could you remove the coin without taking out the cork or breaking the bottle?

I am a mother. However, I never give birth.

I am a father. However, I never nurse my children.

Wandering is not possible for me, but standing still happens occurs rarely.

Who am I?

Can you think of any three-dimensional shape that comprises of exactly two surfaces?

John is found dead in a bare field. Nobody killed John,
John did not commit suicide.

Inspector Jacob found a bag just a few meters away from John which could save his life. What was in the bag?