The slope of a demand curve depends on which units are used to measure price and quantity.

• A. Units used to measure price and quantity.
• B. Units used to measure quantity only.
• C. Units used to measure price only.
• D. Neither price nor quantity units.

Answer: (A)

The slope of a demand curve depends on how you measure price and quantity because slope is the ratio of price change to quantity change along the curve (ΔP/ΔQ). When you change the units for either axis, you change the numerical value of that ratio even though the underlying relationship between price and quantity hasn’t changed.

For example, if you measure price in dollars instead of cents, a change of $1 translates to 100 cents, so the slope becomes 100 times larger. If you measure quantity in units instead of dozens, a 1-dozen change corresponds to 12 units, so the slope becomes 12 times larger as well (since ΔQ' = ΔQ/12, and m' = ΔP/ΔQ' = 12·ΔP/ΔQ). In short, changing either price or quantity units alters the numeric slope, while the actual demand relationship remains the same.

Therefore, the slope depends on the units used to measure both price and quantity.