How to Calculate the Slope of a Demand Curve With a Table

Solving for Slope with Linear Demand Curve Table

• 1

  Write down a set of values for a certain point on the graph from the data provided within the table. For example, if the table states that at point (30, 2) the value of Q = 30, the value of P = 2 and the value of a = 4, write them out on a piece of paper for easy access.

• 2

  Insert the values into the linear demand curve equations, Q = a - bP. For example, using the above values found from the example table, insert Q = 30, P = 2 and a = 4 into the equation: 30 = 4 - 2b.

• 3

  Isolate the b variable on one side of the equation in order to solve for the slope. For example, using algebra we find: 30 = 4 - 2b becomes 30 - 4 = - 2b, becomes -26 = 2b, becomes -26 / 2 = b.

• 4

  Solve for the slope "b" using your calculator or by hand. For example, solving the equation -26 / 2 = b finds b = -13. So, the slope for this set of parameters equals -13.

Using Slope-Intercept Form with a Coordinate Table

• 5

  Write down the x and y values from two points listed on a demand curve's coordinate table. In the case of a demand curve, the point "x" equals the quantity demanded of a product and the point "y" equals the price of the product at that level of demand.

• 6

  Insert these values into the slope equation: slope = change in y / change in x. For example, if the table states that the values of of x1 = 3, x2 = 5, y1 = 2 and y2 = 3, the slope equation is set up like this: slope = (3 - 5) / (2 - 3).

• 7

  Solve the slope equation to find the slope of the demand curve between the two chosen points. For example, if the slope = (3 - 5) / (2 - 3), then slope = -2 / -1 = 2.