1. Let A be a binary relation on the set of human such that x A y ? x is an ancestor of y. Also, assume that every individual is an ancestor of himself.

Is A an order relation (R is an order relation if R is reflexive, anti-symmetric and transitive)? Explain. Show each step of your working.

2. Let R be a binary relation on the set of real numbers such that x R y ? x y > 0.

Is R reflexive? Explain.

Is R symmetric? Explain.

Is R anti-symmetric? Explain.

Is R transitive? Explain.

3. (a) Find the decimal expansion of (1110 1011) base 2. Show your steps. (b) Find the hexadecimal expansion of (74632170) base 8. Show your steps.