Week 4 — Quiz · Supply & Market Equilibrium
Course: Principles of Microeconomics (ECON 1) · Silver Oak University (fictional sample) · Prof. Kessler
Objective 2 · 10 questions · 10 points · closed to AI · one attempt
Auto-graded (Classic QTI): see F-quiz-week-04-qti.xml for the Canvas import. Every numeric answer is pre-computed and independently verified; every curve-shift claim is checked.
The questions (human-readable; answer key below)
Q1. The law of supply states that, all else equal —
A) Producers supply more of a good at lower prices B) Producers supply more of a good at higher prices C) Quantity supplied is unaffected by price changes D) Supply and demand always move in opposite directions
Q2. The price of steel rises sharply. For the auto-manufacturing market, this causes —
A) A movement UP ALONG the supply curve for cars B) A RIGHTWARD shift of the supply curve for cars C) A LEFTWARD shift of the supply curve for cars D) A shift of the demand curve for cars
Q3. For a market with Qd = 80 − 2P and Qs = −10 + 3P, the equilibrium price P* is —
A) $14 B) $16 C) $18 D) $22
Q4. In the market from Q3 (Qd = 80 − 2P, Qs = −10 + 3P, P* = $18), if the price is set at $24, the market has —
A) A shortage of 30 units B) A surplus of 30 units C) A shortage of 62 units D) Equilibrium; price is above P* so the market clears with excess demand
Q5. When the market price is BELOW the equilibrium price, the result is —
A) A surplus that pushes the price down further B) A shortage that pushes the price upward C) A surplus that pushes the price upward D) A shortage that pushes the price downward
Q6. New technology cuts production costs in the solar-panel industry. The most accurate prediction is —
A) Supply shifts left; equilibrium price rises and quantity falls B) Supply shifts right; equilibrium price falls and quantity rises C) Demand shifts right; equilibrium price rises and quantity rises D) Supply shifts right; equilibrium price rises and quantity rises
Q7. The price of wheat (an input) rises. In the bread market, this will —
A) Shift demand for bread to the right, raising price and raising quantity B) Shift supply of bread to the left, raising price and lowering quantity C) Shift supply of bread to the right, lowering price and raising quantity D) Move buyers along the demand curve, lowering quantity demanded
Q8. (Select all that apply.) Which of the following would INCREASE the supply of tomatoes (shift the supply curve to the RIGHT)?
☐ A) A rise in the price of tomatoes ☑ B) A fall in the price of fertilizer ☑ C) Better irrigation technology that raises crop yields ☑ D) An increase in the number of tomato farmers ☐ E) A drought that destroys part of the tomato crop
Q9. (True/False) If demand for a good increases AND supply of the same good also increases simultaneously, the new equilibrium price is definitely higher than before. → False
Q10. (Matching) Input price falls → Supply increases (curve shifts right); A per-unit tax on producers → Supply decreases (curve shifts left); The price of the good itself rises → Quantity supplied rises (movement along curve); New, more efficient technology → Supply increases (curve shifts right). (Distractor: "Demand increases (curve shifts right).")
Answer key & feedback (instructor)
| Q | Type | Answer | Feedback (the idea) |
|---|---|---|---|
| 1 | MC | B | The supply curve slopes upward: higher price → more profitable → more quantity supplied. |
| 2 | MC | C | Steel is an INPUT for cars; a higher input price raises production costs → supply DECREASES (leftward shift). A price-of-steel change is NOT a price of the car itself, so it shifts the curve. |
| 3 | MC | C | Set 80−2P = −10+3P → 90 = 5P → P* = $18. Check: Qd = 80−36 = 44; Qs = −10+54 = 44. ✓ |
| 4 | MC | B | At P=24: Qd = 80−48 = 32; Qs = −10+72 = 62. Surplus = 62−32 = 30. Qs > Qd → surplus → price pressure DOWN. |
| 5 | MC | B | Below eq: Qd > Qs → shortage; buyers compete for the scarce good → sellers raise price → price rises back toward eq. |
| 6 | MC | B | Technology improvement → lower production cost → supply increases → right shift → P↓, Q↑. Distractor D flips the P direction. |
| 7 | MC | B | Wheat is an input for bread → higher input price → cost rises → supply of bread decreases (left shift) → P↑, Q↓. |
| 8 | MA | B, C, D | Lower input cost (B), better tech (C), and more sellers (D) all increase supply (rightward shift). A price rise (A) = movement along curve; a drought (E) = supply decrease (left shift). |
| 9 | TF | False | ↑Demand pushes P up; ↑Supply pushes P down — these forces work against each other. P is indeterminate; only Q is unambiguously higher (both shifts raise quantity). |
| 10 | Match | as above | Key trap: "price of the good rises" → movement along the curve, NOT a shift — the distractor ("demand increases") catches students who confuse which side of the market is moving. |
Quality gate (self-checked): Q3 (90 ÷ 5 = 18) and Q4 (Qd=32, Qs=62, surplus=30) re-computed in Python ✓; supply-shift directions (left for higher input cost; right for lower cost/better tech) verified against the discipline-reference rule: ↑Supply → P↓, Q↑; ↓Supply → P↑, Q↓ ✓; both-shift indeterminacy (Q9) confirmed ✓; no free numeric entry; ≥1 MA, ≥1 TF, ≥1 matching.
F-quiz-week-04-qti.xml) ships inside the course's .imscc package — it lands in the Canvas gradebook on import.~ Prof. Kessler's edition · Fall 2026 · built with thecoursemaker.com