There was a strange boy who was born before his father. How can this be possible?

There are people and strange monkeys on this island, and you can not tell who is who (Edit: until you understand what they said - see below). They speak either only the truth or only lies.
Who are the following two guys?
A: B is a lying monkey. I am human.
B: A is telling the truth.

What is the word or phrase?

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

How many cubic feet of dirt are in a hole of one foot deep, three feet long, and two feet wide?

The average age of 10 members of a committee is the same as it was 4 years ago, because an old member has been replaced by a young member.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

John and Jenni are a married couple. They have two kids, one of them is a girl. Assume safely that the probability of each gender is 1/2.
What is the probability that the other kid is also a girl?

Hint: It is not 1/2 as you would first think.

What's the only room from which no one can enter or leave

Can you count the number of seconds in a year?

Clue: You need to bother about calculation.

If you drop a 15 kg iron bar and a 5 kg bag of cotton from a height of 50 meters which will reach the ground first?