 4. Market Demand
 A. Meaning

 1.
The market demand of a good refers to the quantities that all consumers would buy at various possible prices per time period, other things being constant (i.e. ceteris paribus).
 2 It is the sum of individual demands in a given market.

 B. Derivation of a Market Demand Schedule / Curve
 We can derive the market demand of a good by adding up the quantity demanded by each individual at each price. For illustration, assume that there are only two individual buyers (A and B) in a market:

Price of Good X (\$)
Individual Demand
Market Demand (units)
A (units)
B (units)
 5 4 3 2 1
 1 2 3 4 5
 1 4 7 10 13
 2 6 10 14 18
Derivation of a market demand schedule

 A market demand schedule is obtained by summing up the individual demand schedules. Similarly, we can derive a market demand curve by such "horizontal summation" of individual demand curves, as shown below: Derivation of a market demand curve

 The demand curves for A and B are represented by DA and DB respectively. Adding the two demand curves horizontally, we get the market demand curve for Good : DA+DB .