Why is Saturday stronger than Monday?

I cannot talk, but I always reply when spoken to. What am I?

Railroad Crossing, look out for the cars. Can you spell that, without any R's ?

Three brothers Jacob, John, and James live in Mexico City. The product of the ages of these brothers is 175. Jacob and John are twins. How old is James?

What does below rebus means ?

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.

Samuel was out for a walk when it started to rain. He did not have an umbrella and he wasn't wearing a hat. His clothes were soaked, yet not a single hair on his head got wet. How could this happen?

What begins with T, ends with T, and has T in it?

Can you find the six hidden animals in the picture below?

Is the statement valid that it does not matter how much older a sibling is, eventually the younger one will be half as old as the older one?