**World Population
Models **

The function describes
the world population (in billion) at time t, where t = 0 on January
1, 2000.

**Linear Model **

**Exponential
Model **

**World
Grain Supply **

The supply
function was derived using two factors: area cultivated, measured
in billion hectares, and yield per hectares, measured in kilograms
per hectare. The supply function is

The function
describes the world grain supply (in billion kilograms) at time
t, where t = 0 on January 1, 2000.

**Area **

where t = 0 on January
1, 2000.

**Yield **

where
t = 0 on January 1, 2000.