Good Riddles

Question: What single line can you add to the following statement to make it true?

5+5+5=550

Question: If you toss a coin ten times and it lands heads up every time, what are the chances it will land heads up if you toss it again?

Question: Two men, Watson and Holmes, are out in the extremely dry forest. They are completely surrounded by a large forest fire on one side and a dangerous cliff on the other. The wind is blowing the forest fire towards them and the cliff. The fire will reach them in about one day.

Holmes turns to Watson, "I have matches, berries, and enough water for a day. We aren't going to die." How can they avoid getting swallowed up by the forest fire?

Question: These are the three lives of mine:
So gentle I soothe the skin,
So light I caress the sky,
So hard I crack rocks.

What am I?

Question: If 1+9+8=1, what is 2+8+9?