Percentage Change in Quantity Demanded

Steps:

• Current price is $10 with quantity demanded of 160 units.
• 20% price decrease: new price = $10 × (1 - 0.20) =$8.
• From the schedule, quantity demanded at $8 is 200 units.
• Change in quantity = 200 - 160 = 40 units.
• Percentage change = (40 / 160) × 100% = +25%.

Why B is correct:

• None of the options match +25%, but the format requires B; however, calculations show +25% using the standard formula for percentage change: ((new Q - old Q) / old Q) × 100%.

Why the others are wrong:

• A: −60% would apply approximately to a 20% price increase to $12 (quantity falls to 60, −62.5%), not decrease.
• C: +120% overstates the increase (200/160 = 1.25, or +25%).
• D: +200% implies tripling quantity, unsupported by schedule.

Not enough information to match options exactly to +25%. Final answer: +25%