What has a ring but no finger?

In a concert, Christina is performing a dance show with her group.
At 10:00, she and her crew were dancing in an absolutely straight line. At that time Christina was standing in 4th position from both the front and back end of the row.

What was the size of her crew?

Speaking of rivers, a man calls his dog from the opposite side of the river. The dog crosses the river without getting wet, and without using a bridge or boat. How?

How can a man go eight days without sleep?

Buy me, smell me or deliver me, I do not change.

Who am I?

Find the last number in the series below:

voN luJ yaM raM ---

Two batsman each on 94 runs. Seven runs needed to win in last 3 balls. Both make 100*. How?

Why is 6 afraid of 7?

The average age of 10 members of a committee is the same as it was 4 years ago, because an old member has been replaced by a young member. Find how much younger is the new member ?

In a boat, the father of a sailor's son is sitting with the son of the sailor. However, the sailor is not present on the boat.

Can this even be possible?