Here’s a clear way to think about how different events change the demand for cups of coffee, and how to show it on a standard demand-and-supply graph.

Setup: The basic coffee market graph

Imagine a regular demand-and-supply diagram for cups of coffee:

  • Horizontal axis: Quantity of coffee (cups per day).
  • Vertical axis: Price per cup.
  • Downward-sloping curve: Demand (D).
  • Upward-sloping curve: Supply (S).
  • Where D and S intersect: equilibrium price and quantity.

When an event changes demand , the whole demand curve shifts :

  • Increase in demand → demand curve shifts right (D to D₁).
  • Decrease in demand → demand curve shifts left (D to D₁).
    Supply stays in the same place for these demand questions.

Typical events and how to draw them

I’ll walk through common textbook-style events that affect the demand for coffee and describe exactly how to sketch them. If your question lists specific events, match them to the closest case below.

1. Increase in consumers’ income (coffee is a normal good)

Story: People earn more, so they’re more willing and able to buy coffee at any given price. Graph:

  • Original demand: D.
  • New demand: D₁ shifted to the right.
  • Supply S unchanged.
  • New equilibrium: higher equilibrium quantity and higher equilibrium price.

How to label:

  • Draw D and S intersecting at point E.
  • Draw a new demand curve D₁ to the right of D, intersecting S at E₁.
  • Mark P₁ > P and Q₁ > Q.

2. Decrease in consumers’ income (coffee is a normal good)

Story: Incomes fall (recession, job loss), people cut back on café purchases and maybe brew less premium coffee. Graph:

  • Demand curve shifts left : D → D₁.
  • Supply S unchanged.
  • New equilibrium: lower price and lower quantity.

If your instructor says coffee is an inferior good , flip this: a fall in income would shift demand right instead.

3. Rise in the price of a substitute (e.g., tea or energy drinks)

Story: Tea or energy drinks become more expensive, so some consumers switch to coffee. Graph:

  • Demand for coffee increases.
  • Demand curve shifts right : D → D₁.
  • Supply S unchanged.
  • New equilibrium: higher price, higher quantity.

To sketch:

  • Start with D and S.
  • Draw D₁ to the right of D.
  • Show the new intersection at a higher P and Q.

4. Fall in the price of a substitute

Story: Tea or energy drinks get cheaper, so some consumers move away from coffee. Graph:

  • Demand for coffee decreases.
  • Demand curve shifts left : D → D₁.
  • Supply S unchanged.
  • New equilibrium: lower price and lower quantity.

5. Fall in the price of a complement (e.g., pastries, milk)

Story: Coffee and pastries (or milk) are often consumed together. If pastries get cheaper, people buy more pastries and also more coffee to go with them. Graph:

  • Demand for coffee increases.
  • Demand curve shifts right : D → D₁.
  • Supply S unchanged.
  • Price and quantity both rise at the new equilibrium.

6. Rise in the price of a complement

Story: Milk or pastries become more expensive; people cut those purchases and therefore also cut coffee that goes with them. Graph:

  • Demand for coffee decreases.
  • Demand curve shifts left : D → D₁.
  • Supply S unchanged.
  • Price and quantity both fall.

7. A health study says coffee has big health benefits

Story: Preferences change in favor of coffee; people want more coffee at every price. Graph:

  • Demand curve shifts right.
  • Supply unchanged.
  • New equilibrium: higher price and higher quantity.

You can think of this as a “taste and preferences” shock.

8. A health warning says coffee is harmful

Story: Preferences shift against coffee; some people reduce or stop consumption. Graph:

  • Demand curve shifts left.
  • Supply unchanged.
  • New equilibrium: lower price and lower quantity.

9. Growth in population (more potential coffee drinkers)

Story: More people in the market (e.g., more adult population, more students), so total market demand rises. Graph:

  • Demand curve shifts right.
  • Supply unchanged.
  • Higher equilibrium price and quantity.

10. A fall in population, or fewer coffee drinkers (e.g., shift to other

beverages)

Story: Fewer people in the coffee market, or generational preference shifts away from coffee. Graph:

  • Demand curve shifts left.
  • Supply unchanged.
  • Lower equilibrium price and quantity.

11. Seasonal or time-of-day change (e.g., winter vs summer)

Story:

  • In winter (or exam season), people often drink more hot coffee.
  • In summer, some may switch to iced drinks or non-coffee beverages unless iced coffee demand offsets this.

Graph:

  • Winter / exam season: demand rightward shift.
  • Off-season: demand leftward shift.

You’d draw separate graphs (or multiple demand curves on one graph) to show high-demand vs low-demand periods.

How to present your answer in an exam

For each event:

  1. Write a one-line explanation of why demand rises or falls:
    • “Income increases → coffee is a normal good → demand increases (rightward shift).”
  2. Draw the same base graph :
    • Axes labeled.
    • Original curves: D, S, equilibrium at (P, Q).
  3. Show the new demand curve :
    • Label it D₁.
    • Shift right for increase, left for decrease.
  4. Mark the new equilibrium :
    • New intersection: E₁.
    • Label new price P₁ and quantity Q₁.
  5. Optionally add a brief note under the graph:
    • “Result: P₁ > P, Q₁ > Q (increase in demand).”

Mini story illustration

Imagine a university town:

  • It’s winter exam week, and a new study says moderate coffee improves focus. Students have a bit more money from part-time jobs.
  • Income up, preferences for coffee stronger, and it’s cold outside.

All three forces push demand for coffee to the right :

  • Lines in front of coffee shops get longer.
  • Shops raise prices a bit but still sell more cups than before.
  • Your graph shows D shifting to D₁, new equilibrium with higher price and higher quantity.

SEO-style summary (for your “Quick Scoop” post)

  • The key phrase “illustrate graphically how each of the following events will impact the demand for cups of coffee” refers to demand curve shifts , not movements along the curve.
  • Events that make people want more coffee at each price (higher income for a normal good, higher price of substitutes, lower price of complements, positive health news, more consumers) shift demand right.
  • Events that make people want less coffee at each price (lower income for a normal good, lower price of substitutes, higher price of complements, negative health news, fewer consumers) shift demand left.
  • In each case, supply remains fixed and the new intersection of demand and supply gives the new price and quantity.

Information gathered from public forums or data available on the internet and portrayed here.