AP Microeconomics Quiz: Other Elasticities

What this quiz covers

This quiz focuses on Other Elasticities, giving you a quick way to practice the rules, question types, and explanations that matter most for AP Microeconomics.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. Substitutes because XED is negative.
2. Complements because XED is negative. (correct answer)
3. Unrelated because XED is positive.
4. Substitutes because XED is positive.
5. Unrelated because popcorn demand fell when the price of popcorn rose.

Explanation: This question examines cross-price elasticity of demand (XED) between popcorn and movie tickets. XED measures how quantity demanded of one good responds to price changes of another, with negative values indicating complements and positive values indicating substitutes. Movie ticket prices rise 20% while popcorn quantity falls 10%, yielding XED = -10%/+20% = -0.5. The negative XED confirms these are complementary goods—people buy popcorn when attending movies, so higher movie prices reduce both movie attendance and popcorn purchases. Students often confuse this with own-price elasticity (where popcorn's own price affects popcorn demand). For XED problems: identify which good's price changed and which good's quantity changed, calculate the sign, then interpret (negative = complements, positive = substitutes).

Question 2

1. Complements, because XED is positive
2. Unrelated, because XED equals zero
3. Substitutes, because XED is positive (correct answer)
4. Complements, because XED is negative
5. Substitutes, because quantity demanded rises when its own price rises

Explanation: This question involves cross-price elasticity of demand (XED). XED measures how the quantity demanded of one good changes in response to a price change in another good, with positive XED indicating substitutes, negative indicating complements, and zero indicating unrelated. Here, the price of tea increases by 10%, and the quantity demanded of coffee increases by 10%, resulting in XED = 10%/10% = 1. Since XED is positive, coffee and tea are substitutes, as demand for one rises when the other's price increases. A common misconception is mixing XED signs with YED, but XED focuses on cross-good price effects. To analyze similar problems, first determine the sign of the elasticity coefficient. Then, match it to the categories: positive for substitutes, negative for complements.

Question 3

1. Normal, because YED is negative
2. Inferior, because YED is negative (correct answer)
3. Normal, because YED is positive
4. Unrelated to income, because YED equals zero
5. Inferior, because quantity demanded falls when price rises

Explanation: This question involves income elasticity of demand (YED). YED measures how the quantity demanded of a good changes in response to a change in income, with a positive YED indicating a normal good and a negative YED indicating an inferior good. Here, income increases by 10%, and the quantity demanded of soup decreases by 10%, resulting in YED = -10%/10% = -1. Since YED is negative, soup is an inferior good, as demand falls with rising income. A common misconception is assuming negative YED means normal, but the sign directly indicates inferiority. To analyze similar problems, first determine the sign of the elasticity coefficient. Then, match it to the categories: negative for inferior goods, positive for normal.

Question 4

1. Normal good because the income elasticity is positive. (correct answer)
2. Inferior good because the income elasticity is positive.
3. Inferior good because the income elasticity is negative.
4. Normal good because the income elasticity is negative.
5. Normal good because the income elasticity equals zero.

Explanation: This question tests income elasticity of demand (YED) for bus rides. YED measures how quantity demanded responds to income changes, where positive YED indicates a normal good and negative YED indicates an inferior good. The data shows that when income falls by 10%, bus ride demand falls from 1,000 to 950 rides (a 5% decrease), yielding YED = -5%/-10% = +0.5. The positive sign confirms that bus rides are a normal good in this situation—consumers reduce their bus usage when income falls, suggesting they view bus transportation as something they want to maintain when they can afford it. A common misconception is assuming all public transportation must be inferior goods, but the classification depends on the specific market and consumer base. To determine good types, calculate YED's sign: when income and quantity move in the same direction (both up or both down), YED is positive, indicating a normal good. This finding might reflect a market where bus riders have limited alternative transportation options.

Question 5

1. Normal because YED is positive. (correct answer)
2. Inferior because YED is positive.
3. Inferior because YED is negative.
4. Unrelated because YED is zero.
5. Normal because demand rises when price rises.

Explanation: This question examines income elasticity of demand (YED) for used clothing. YED measures how quantity demanded responds to income changes, where positive values indicate normal goods and negative values indicate inferior goods. Income rises from $3,000 to $3,300 (10% increase) and used clothing rises from 10 to 11 items (10% increase), giving YED = +10%/+10% = +1.0. The positive YED indicates used clothing is a normal good for this consumer—contrary to common assumptions that used goods are inferior. A frequent error is assuming all second-hand goods must be inferior goods, but elasticity measures actual behavior, not stereotypes. To solve YED problems: calculate percentage changes, determine the sign (positive = normal), and avoid preconceptions about good types.

Question 6

1. Substitutes because XED is positive. (correct answer)
2. Complements because XED is positive.
3. Unrelated because XED is negative.
4. Complements because XED is negative.
5. Substitutes because demand for tea falls when coffee becomes more expensive.

Explanation: This question tests cross-price elasticity of demand (XED) between tea and coffee. XED measures how quantity demanded of one good (tea) responds to price changes of another good (coffee), where positive XED indicates substitutes and negative XED indicates complements. Coffee price rises 10% and tea quantity rises 5%, giving XED = +5%/+10% = +0.5. The positive XED confirms tea and coffee are substitutes—when coffee becomes more expensive, consumers switch to tea. A common mistake is thinking positive XED means complements (it's actually the opposite). To solve XED problems: calculate the sign first (positive = substitutes, negative = complements), then verify the logic makes economic sense.

Question 7

1. Substitutes because XED is positive.
2. Complements because XED is negative.
3. Unrelated because XED is zero. (correct answer)
4. Complements because XED is zero.
5. Substitutes because peanut butter is more expensive.

Explanation: This question examines cross-price elasticity of demand (XED) between jelly and peanut butter. XED measures how quantity demanded of one good responds to price changes of another good, where positive indicates substitutes, negative indicates complements, and zero indicates unrelated goods. Peanut butter price rises 10% but jelly quantity remains unchanged (0%), giving XED = 0%/10% = 0. The zero XED indicates these goods are unrelated in this consumer's preferences—surprising given they're often complements. Students might assume all paired foods must be complements, but elasticity measures actual consumer behavior, not assumptions. For XED problems: calculate the actual elasticity value first, then interpret based on the sign (positive = substitutes, negative = complements, zero = unrelated).

Question 8

1. Normal, because YED is positive
2. Inferior, because YED is positive
3. Inferior, because YED is negative (correct answer)
4. Normal, because YED is negative
5. Unrelated to income, because quantity demanded changes when price changes

Explanation: This question involves income elasticity of demand (YED). YED measures how the quantity demanded of a good changes in response to a change in income, with a positive YED indicating a normal good and a negative YED indicating an inferior good. Here, income decreases by 10%, and the quantity demanded of bus passes increases by 10%, resulting in YED = 10%/-10% = -1. Since YED is negative, bus passes are an inferior good, as demand rises when income falls. A common misconception is assuming a demand increase with falling income means normal, but the negative sign confirms inferiority. To analyze similar problems, first determine the sign of the elasticity coefficient. Then, match it to the categories: negative for inferior, positive for normal.

Question 9

1. A negative YED implies tickets are an inferior good; consumers buy fewer as income rises.
2. A positive YED implies tickets are a normal good; consumers buy more as income rises. (correct answer)
3. A zero YED implies tickets are unrelated to income; consumers buy more as income rises.
4. A positive YED implies tickets are an inferior good; consumers buy fewer as income rises.
5. A negative YED implies tickets are a normal good; consumers buy more as income rises.

Explanation: This question tests income elasticity of demand (YED) for movie theater tickets. YED measures how quantity demanded responds to income changes, where positive YED indicates a normal good (consumed more as income rises) and negative YED indicates an inferior good. The data shows that when income rises by 25%, ticket demand increases from 400 to 420 tickets (a 5% increase), yielding YED = +5%/+25% = +0.2. The positive sign confirms that movie tickets are a normal good—consumers purchase more entertainment as their income increases. A common misconception is confusing the sign interpretation: some students think negative YED means "bad" and positive means "good," but it's about consumption patterns, not quality. To interpret YED correctly, focus on the sign first: positive means normal (income and quantity move together), negative means inferior (income and quantity move oppositely). The relatively low elasticity (0.2) suggests movie tickets are a necessity within entertainment spending.

Question 10

1. XED is negative; coffee and tea are complements.
2. XED is positive; coffee and tea are substitutes. (correct answer)
3. XED is zero; coffee and tea are unrelated.
4. XED is positive; coffee and tea are complements.
5. XED is negative; coffee and tea are substitutes.

Explanation: This question asks about cross-price elasticity of demand (XED) for coffee with respect to tea's price. XED measures how the quantity demanded of one good responds to price changes in another good, where positive XED indicates substitutes and negative XED indicates complements. Here, tea's price rises by 10% and coffee's quantity demanded rises by 5%, giving XED = (+5%)/(+10%) = +0.5. The positive sign means coffee and tea are substitutes—when tea becomes more expensive, consumers switch to coffee. A common error is confusing the sign: some think goods consumed together must have positive XED, but complements actually have negative XED (when one's price rises, demand for both falls). To avoid mistakes, always check the sign first: if price and quantity move in the same direction (both up or both down), XED is positive (substitutes); if they move oppositely, XED is negative (complements).

Question 11

1. XED is positive; hamburgers and hot dogs are substitutes.
2. XED is negative; hamburgers and hot dogs are complements.
3. XED is zero; hamburgers and hot dogs are unrelated. (correct answer)
4. XED is negative; hamburgers and hot dogs are substitutes.
5. XED is positive; hamburgers and hot dogs are complements.

Explanation: This question analyzes cross-price elasticity of demand (XED) for hamburgers with respect to hot dog prices. XED reveals relationships between goods: positive for substitutes, negative for complements, and zero for unrelated goods. When hot dog prices rise by 10% but hamburger quantity demanded remains unchanged (0% change), XED = (0%)/(+10%) = 0. Zero XED indicates hamburgers and hot dogs are unrelated goods—consumers don't view them as substitutes or complements in their consumption decisions. Students often assume all food items must be substitutes, but zero XED is possible when goods serve different purposes or appeal to different preferences. The key insight is that not all goods in the same category necessarily interact in consumer choice. When quantity demanded shows no response to another good's price change, the goods are independent in the market.

Question 12

1. YED is positive; consumers buy more of Good Z as income rises.
2. YED is negative; consumers buy less of Good Z as income rises.
3. YED is zero; consumers buy the same amount of Good Z as income changes. (correct answer)
4. YED is positive; consumers buy less of Good Z as income rises.
5. YED is negative; consumers buy the same amount of Good Z as income changes.

Explanation: This question involves income elasticity of demand (YED). YED measures how the quantity demanded of a good changes in response to a change in income, with a positive sign indicating a normal good and a negative sign indicating an inferior good. Here, income increases by 25%, and the quantity demanded of Good Z increases by 0%, with prices held constant. This results in a zero YED because the percentage change in quantity is zero divided by the positive percentage change in income, implying consumer behavior toward Good Z is unaffected by income changes. A common misconception is confusing zero YED with negative YED, but zero means no responsiveness, not a decrease in demand. To analyze similar problems, first determine the sign of YED by comparing the directions of income and quantity changes. Then, match the sign to the category: positive for normal, negative for inferior, and zero for income-independent goods.

Question 13

1. They are complements because ink demand falls when printer prices rise, implying negative XED. (correct answer)
2. They are substitutes because ink demand falls when printer prices rise, implying positive XED.
3. They are unrelated because only ink quantity changed.
4. They are substitutes because both goods are used together.
5. They are complements because the demand curve for ink must slope upward.

Explanation: This question tests cross-price elasticity of demand (XED) between printers and ink cartridges. XED measures how quantity demanded of one good responds to price changes in another, with negative values indicating complements and positive values indicating substitutes. The data shows ink cartridge quantity falls from 200 to 150 units (-25% change) when printer prices rise by 25%, yielding XED = -25%/+25% = -1.0. The negative XED confirms these goods are complements—when printers become more expensive, fewer people buy printers, so they also need less ink. A common error is thinking goods that work together must be substitutes, but complementary goods show opposite movements: one's price up means the other's quantity down. To analyze XED systematically: calculate the sign first, then remember negative means complements (used together) and positive means substitutes (used instead of each other).

Question 14

1. They are complements because bicycle rentals rise when gasoline becomes more expensive.
2. They are unrelated because gasoline and bicycle rentals are different markets.
3. They are substitutes because bicycle rental demand rises when gasoline prices rise, implying positive XED. (correct answer)
4. They are complements because XED is negative when one price rises.
5. They are substitutes because the demand curve for bicycle rentals must be perfectly elastic.

Explanation: This question tests cross-price elasticity of demand (XED) between gasoline and bicycle rentals. XED reveals the relationship between goods through the sign of the elasticity: positive for substitutes, negative for complements. The data shows bicycle rentals rise from 300 to 360 per week (+20% change) when gasoline prices rise by 20%, yielding XED = +20%/+20% = +1.0. The positive XED confirms these transportation modes are substitutes—people switch to bicycles when driving becomes more expensive. A common error is assuming XED must be negative whenever any price rises, but the key is whether the goods serve similar purposes (substitutes) or are used together (complements). To solve XED problems efficiently: first check if the quantity change moves in the same direction as the price change (positive XED = substitutes) or opposite direction (negative XED = complements).

Question 15

1. Substitutes, because the quantity of ink cartridges rises when the price of printers falls.
2. Unrelated, because quantities and prices moved in opposite directions.
3. Complements, because XED is negative. (correct answer)
4. Substitutes, because XED is negative.
5. Complements, because XED is positive.

Explanation: This question tests cross-price elasticity of demand (XED) between printers and ink cartridges. XED reveals whether goods are substitutes (positive XED) or complements (negative XED) based on how quantity demanded of one responds to price changes in the other. The data shows printer price fell 20% and ink cartridge quantity rose 10%, yielding XED = +10%/-20% = -0.5. Since XED is negative, printers and ink cartridges are complements—cheaper printers lead to more printer purchases, which drives up ink cartridge demand. A common mistake is focusing only on the direction of quantity change without considering the price change direction; when price falls and quantity of the other good rises, that's actually a negative relationship. To avoid errors, always calculate XED with proper signs, then interpret: negative = complements (used together), positive = substitutes (used instead of each other). This matches real-world usage patterns.

Question 16

1. YED is negative, so bottled water is an inferior good.
2. YED is positive and less than 1, so bottled water is a normal good and income-inelastic. (correct answer)
3. YED equals 1, so bottled water is unit income-elastic.
4. YED is positive and greater than 1, so bottled water is a luxury good.
5. YED is zero, so bottled water demand depends only on price.

Explanation: This question tests income elasticity of demand (YED) for bottled water. YED measures responsiveness of quantity demanded to income changes, where positive values indicate normal goods and the magnitude shows whether they're necessities (YED < 1) or luxuries (YED > 1). The data shows income rose 10% and bottled water quantity rose 2%, yielding YED = +2%/+10% = +0.2. Since YED is positive but less than 1, bottled water is a normal good that's income-inelastic (a necessity)—people buy somewhat more as income rises, but not proportionally. A common error is thinking any positive response means luxury status, but luxuries require YED > 1. To categorize goods correctly, first check the sign (positive = normal, negative = inferior), then if positive, check magnitude (< 1 = necessity, > 1 = luxury). This systematic approach prevents classification errors.

Question 17

1. Supply is more elastic in the long run because construction allows larger quantity adjustments over time. (correct answer)
2. Supply is more elastic in the short run because firms can instantly build new apartments.
3. Supply is perfectly elastic in the short run because quantity supplied increased.
4. Supply is perfectly inelastic in the long run because rents did not change further.
5. Supply is more elastic in the short run because the percent change in quantity is smaller later.

Explanation: This question tests elasticity of supply over different time periods for apartment units. Supply elasticity measures quantity supplied responsiveness to price changes, typically increasing over time as producers gain adjustment flexibility. Initially, a 10% rent increase yields only 1% more apartments (elasticity = 0.1), but after two years the same 10% rent increase sustains 9% more supply (elasticity = 0.9). Supply is more elastic in the long run because developers need time to acquire land, get permits, and construct buildings—constraints that severely limit short-run responses. A common error is thinking any positive response means elastic supply, but comparing time periods shows how dramatically responsiveness improves. To analyze supply elasticity over time, calculate elasticity at each period using the same price change. Higher elasticity values in later periods confirm that supply constraints relax over time, allowing quantity to adjust more fully.

Question 18

1. YED is positive; bus rides are a normal good.
2. YED is negative; bus rides are an inferior good. (correct answer)
3. YED is zero; bus rides are unrelated to income.
4. YED is negative; bus rides are a normal good.
5. YED is positive; bus rides are an inferior good.

Explanation: This question examines income elasticity of demand (YED) for bus rides. YED measures how quantity demanded responds to income changes, where positive YED indicates normal goods and negative YED indicates inferior goods. The data shows income rises by 20% while bus rides demanded falls by 10%, yielding YED = (-10%)/(+20%) = -0.5. The negative sign classifies bus rides as an inferior good—as income increases, consumers substitute away from bus rides to preferred alternatives like personal vehicles. A frequent misconception is thinking all goods must be normal (positive YED), but inferior goods are common for basic necessities or lower-quality substitutes. When calculating YED, focus on the sign first: positive means consumers buy more as they get richer (normal), while negative means they buy less (inferior).

Question 19

1. Complements because XED is positive.
2. Substitutes because XED is positive. (correct answer)
3. Substitutes because XED is negative.
4. Complements because XED is negative.
5. Unrelated because the price of styluses did not change.

Explanation: This question tests cross-price elasticity of demand (XED) between styluses and tablets. XED measures how quantity demanded of one good (styluses) responds to price changes of another (tablets), where positive values indicate substitutes and negative values indicate complements. Tablet prices rise 15% and stylus quantity rises 3%, giving XED = +3%/+15% = +0.2. The positive XED indicates these are substitute goods—when tablets become more expensive, some consumers switch to alternatives that use styluses instead. This seems counterintuitive since styluses are often used with tablets, but the data suggests these consumers view them as alternatives. For XED problems: always calculate from the actual data given, check the sign (positive = substitutes), and remember that elasticity reveals actual behavior, not assumptions.

Question 20

1. Inferior good because the income elasticity is negative. (correct answer)
2. Normal good because the income elasticity is negative.
3. Normal good because the income elasticity is positive.
4. Inferior good because the income elasticity is positive.
5. Inferior good because the income elasticity equals zero.

Explanation: This question tests income elasticity of demand (YED) for instant noodles. YED measures how quantity demanded responds to income changes, where positive YED indicates a normal good and negative YED indicates an inferior good. The data shows that when income rises by 10%, quantity demanded of instant noodles falls from 200 to 180 units (a 10% decrease), yielding YED = -10%/+10% = -1.0. The negative sign confirms that instant noodles are an inferior good—consumers buy less as their income increases, likely switching to higher-quality food options. A common misconception is thinking that any good people buy must be "normal," but inferior goods are those we consume less of as we become wealthier. To correctly classify goods, focus on the sign of YED first: negative means inferior (income up, quantity down), positive means normal (income up, quantity up). This pattern helps explain why discount stores may see reduced sales during economic booms.