Demand
- Numerical Analysis -

Situation:

From past experience, a publisher knows that a particular type of book will sell 14,000 copies at a price of $20 each. Market research further indicates that for every one-dollar increase in price, sales will fall by 400 copies. The publisher asks for your advice in deciding the suggested retail price of the next book published.1

Numerical Analysis:

From a symbolic analysis of the situation, a function used to model this situation is given by R(x) = (14000 - 400x)(20 + x), where x represents the number of increases and R(x) is the anticipated revenue. A table of data may be constructed by substituting values for x into the expression and calculating values for R(x).

Revenue Data

Increases
(x)

Books Sold
(14000-400x)

Price of Book
(20+x)

Revenue
(14000-400x)(20+x)

0

14,000

$20

$280,000

1

13,600

$21

$285,600

2

13,200

$22

$290,400

3

12,800

$23

$294,400

4

12,400

$24

$297,600

5

12,000

$25

$300,000

6

11,600

$26

$301,600

7

11,200

$27

$302,400

8

10,800

$28

$302,400

9

10,400

$29

$301,600

10

10,000

$30

$300,000

11

9,600

$31

$297,600

12

9,200

$32

$294,400

13

8,800

$33

$290,400

14

8,400

$34

$285,000

15

8,000

$35

$280,000

16

7,600

$36

$273,600

17

7,200

$37

$266,400

18

6,800

$38

$258,400

19

6,400

$39

$249,600

20

6,000

$40

$240,000

As can be seen from the table above, the revenue without increasing the suggested retail price of the book would be expected to be $280,000. For the first few times the price is increased the revenue also increases. The revenue reaches a maximum value of $302,400 for seven and eight increases.

Further analysis of this situation may be accomplished by graphing the function listed above or by a symbolic analysis. The numerical analysis may be modeled effectively on the TI-83 graphics calculator.


1

Problems of this type may be found in Mathematical Analysis, 3rd. Ed. By Arya and Lardner, published by Prentice Hall, 1989, page 93.


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