At a used book store, Kathy paid $15 to buy a used book for which she was willing to
pay $ 18. If a new book costs $ 37. Kathy's consumer surplus is

-$19.

Explanation:

From the question, we are given the following parameters or data and they are;

=> The Amount Kathy paid = $15.

=>The amount that Kathy was willing to = pay $ 18.

=> Price of new book= $ 37.

Therefore, we will make use of expression below to calculate the value for the Consumer surplus.

Consumer surplus = MP – AP (1).

Where MP = maximum price a consumer is willing to pay = $18 and AP = Actual price of a particular goods or commodity = $37.

Consumer surplus= $18 - $ 37 = -$19.

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