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).

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).

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.

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.

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.

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 gasoline increases by 10%, and the quantity demanded of public transit increases by 5%, resulting in XED = 5%/10% = 0.5. Since XED is positive, public transit and gasoline are substitutes, as demand for transit rises when gasoline price increases. A common misconception is confusing positive XED with complements, but the sign indicates substitution. To analyze similar problems, first determine the sign of the elasticity coefficient. Then, match it to the categories: positive for substitutes, negative for complements.

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.

This question examines income elasticity of demand (YED) for restaurant meals. YED measures how quantity demanded responds to income changes, where positive values indicate normal goods, and values greater than 1 indicate luxury goods. Income rises 25% and restaurant meals also rise 25%, giving YED = +25%/+25% = +1.0. The positive YED confirms restaurant meals is a normal good, and the value of exactly 1 indicates unit income elasticity—spending on restaurants rises proportionally with income. A common error is confusing YED = 1 with inferior goods or thinking it means the good is unrelated to income. To interpret YED: first check if positive (normal) or negative (inferior), then examine the magnitude (>1 = luxury, <1 = necessity, =1 = unit elastic).

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.

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.