A Scientist was fifty years old in the year 2000 but he was forty years old in the year 2010. How can this be possible?

PS: It has a logical answer.

How many bananas can you eat if your stomach is empty?

A mother is 21 years older than her child. In exactly 6 years from now, the mother will be exactly 5 times as old as the child.
Where's the father?

1 + 9 + 8 = ?
considering, 28 + 8 + 92 = 10

John and his wife were living in a rural place. On a particular day, John's wife fell ill and he called the local doctor. When the doctor picked up, he said, "Doctor, my wife is ill. She might have appendicitis."

"This can't be possible! I took out her appendix two years ago myself," the doctor explained.

When diagnosed, John's wife was found to have appendicitis. How can this be possible?

Assume there are approximately 5,000,000,000 (5 billion) people on Earth. What would you estimate to be the result, if you multiply together the number of fingers on every person's left hand? (For the purposes of this exercise, thumbs count as fingers, for five fingers per hand.) If you cannot estimate the number then try to guess how long the number would be.

A guard is positioned at the one side of the bridge saying ‘A’. His task is to shoot all those who try to leave from ‘A’ to the other side and say ‘B’. He also need to welcome the person who comes from another side ‘B’ to his side ‘A’. The guard comes out of his post every 1 hour and looks down the bridge for any people trying to leave. You are at side ‘A’ and wish to go to another side ‘B’. you also know that it would take 1:45 hr to cross the bridge. How will you cross the bridge?

A Monkey, a squirrel, and an Eagle are racing to the top of the mango tree. Assuming all these animals are in perfect shape, Which animal will reach to Banana first?

If you paint a brown house white it will become a white house. If the stoplight changes from red to green, then the light is green. So, if you throw a white shirt into the Red Sea, what will it become?

Before Balboa discovered the Pacific Ocean, which was the largest ocean before that?