What is common among 11, 69, and 88?

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?

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

How can this be possible?

You are presented with three boxes. One of them has a red ball inside and the other two have a black ball inside each of them. You are asked to pick up the one with red ball and you pick one. Now, one of the other boxes is opened and it is found to have a black ball.

You are presented with a chance to change your box with the one that is left closed. Will you change your box? Why or why not?

Baseball bat and ball cost $100. If the bat cost $99 more than the ball, what is the cost of each?

John was piloting a plane behind a car but was never able to overtake it. Why?

Take away my first letter, then take away my second letter. Then take away the rest of my letters, yet I remain the same. What am I?

By what process could you make a 'Tea-Table' into food?

Why did the Girl throw the butter out of the window?

For this puzzle, you might have to find logic in something illogical. But hey, it's fun and a healthy little break from your strenuous puzzle-solving sessions.

Can you decipher the meaning in the following cluster of letters?

ITIT,NCENTCENT