# AP Microeconomics : Quantity Equilibrium

## Example Questions

### Example Question #2 : Long Run Market Equilibrium

If good X and good Y are substitutes, an increase in the price of good X will lead to which of the following?

a decrease in supply for good Y

an increase in supply for good Y

an increase in demand for good Y

a decrease in demand for good Y

an increase in demand for good Y

Explanation:

The change in price of a substitute good shifts demand.

An increase in the price of good X prompts consumers to use good Y instead of good X (i.e. substituting good X for good Y), resulting in increased demand for good Y.

### Example Question #2 : Quantity Equilibrium

As consumption of a particular good increases, the satisfaction gained from consuming one additional unit of the good eventually ___________.

decreases

increases

equals 1

equals 0

decreases

Explanation:

The law of diminishing marginal utility states that as consumption of a particular good increases, the satisfaction gained from consuming one additional unit (i.e. the marginal utility of the good) eventually decreases.

For example, consider eating chocolate bars. The increase in satisfaction resulting from eating the first chocolate bar is probably higher than the increase in satisfaction from eating the 12th chocolate bar. In other words, the marginal utility has decreased.

### Example Question #3 : Quantity Equilibrium

If the market for Good X is in equilibrium, which of the following would NOT cause a decrease in demand for Good X?

Consumers expect that the price of Good X will decrease.

A newspaper reports that Good X is harmful to the health of consumers.

The number of buyers of Good X decreases.

The price of a substitute good increases.

The price of a substitute good decreases.