Use only one mathematical symbol and all numbers (0-9) to get a sum of 99

On rolling two dices (six-sided normal dice) together, what is the probability that the first one comes up with a 2 and the second one comes up with a 5?

With pointed fangs I sit and wait; with piercing force I crunch out fate; grabbing victims, proclaiming might; physically joining with a single bite. What am I?

Solve the counting riddle by identifying the number of triangles in the given picture.

A father's child, a mother's child, yet no one's son.

Who am I?

John went to meet his friend Jacob, but when he was about to reach the main gate, John notices that Jacob had a mighty dog who was fastened to the tree. The chain is long enough that it allows the dog to reach the main gate.

How can the John reach the main gate?

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

With the help clues provided in the image, can you find the 5 digit key?

A train full of passengers goes through a tunnel. When the train comes out from the other end, there is no single person on the train.

How did it happen?

A doctor and a boy were fishing. The boy was the doctor’s son, but the doctor was not the boy’s father. Who was the doctor?