Who gains from trade, and when is it efficient?
See how buyer values and seller costs become surplus areas, and why too little or too much trade loses gains. Then practise with 10 questions and worked answers.
A buyer’s value sets the most they will pay
| Buyer | Value | Buy? | Surplus |
|---|---|---|---|
| A | $48 | Yes | ? |
| B | $36 | Yes | ? |
| C | $28 | Yes | ? |
| D | $20 | No | ? |
| Total | 3 | ? |
A buyer’s value sets the most they will pay
Buyer values at a stated price
| Buyer | Value | Buy? | Surplus |
|---|---|---|---|
| A | $48 | ? | ? |
| B | $36 | ? | ? |
| C | $28 | ? | ? |
| D | $20 | ? | ? |
| Total | ? | ? |
Exam coming up and the surplus triangles still blur together?
Bring your problem sets. We work through them together until every type feels routine.
Questions, answered.
Still unsure about something? Message us and you will hear back within a day.
See all questionsIn person, we meet at the SFU Burnaby campus or in a private meeting room near Brentwood in Burnaby. Online sessions run on Zoom. You choose when you book.
Create a free account, pick your course and a time, and send the request. We review it and confirm by email within 24 hours. The email has your time and place, or your Zoom link for online sessions.
After the session. Nothing is charged when you book.
Tell us within 24 hours and you get a full refund. No forms, no arguing.
Yes, and it is free. Open your account page and choose "Change time or notes" or "Cancel session", or message us on WhatsApp.
SFU Beedie accounting, finance, statistics and economics courses. The full list is on the Courses page. If yours is missing, message us and we will tell you within a day whether we can cover it.
Yes. Two or more students taking the same course can book together and each pays less per hour. Exam prep packages are also available before midterms and finals.
Yes. After each session you get an email report with what was covered, what to practise next and any files from the session. You can re-read them on your account page.