How each table is made
Every cost table starts from a marginal cost that falls and then rises, so AVC and AC come out U-shaped and MC cuts each at its lowest point, as the textbooks say it must. Product tables have MP rising, then falling and often turning negative, and TP never climbs again once it has started to fall. When the price has to fall to sell more, MR drops faster than the price and goes below zero. Some tables step output up by 2, 5 or 10 units at a time; MC is then the change in TC divided by that step.
An example: set SMC59K
Problem 1 gives TC from Rs 20 at zero output to Rs 99 at 6 units. TFC is TC at zero output, Rs 20, at every output. At 3 units: TVC = 51 − 20 = 31, AFC = 20 ÷ 3 ≈ 6.67, AVC = 31 ÷ 3 ≈ 10.33, SAC = 51 ÷ 3 = 17 and SMC = 51 − 42 = 9. AVC is lowest at 3 units: SMC is 9 there, below AVC, and 11 at 4 units, above it. SAC is lowest at 4 units (15.5), and SMC rises past it to 16 at 5 units. Open set SMC59K
What each course calls it
CBSE class 11 follows NCERT Introductory Microeconomics chapters 3 and 4: SAC and SMC, prices in rupees, super-normal profit, and the shut down point at the lowest AVC. Cambridge 9708 (topic 7.5) uses ATC and MC, with normal, subnormal and supernormal profit. AQA A-level uses AC and MC, normal and abnormal profit and the MC = MR rule; its specification has no shutdown condition, so AQA sets leave it out. AP Microeconomics uses ATC and MC, economic profit and loss, and shuts down when price is below AVC.
Questions
How do you calculate AFC, AVC and MC from total cost?
TFC is TC at zero output, and TVC = TC − TFC. Then AFC = TFC ÷ Q, AVC = TVC ÷ Q and AC = TC ÷ Q. MC is the change in TC from one row to the next, divided by the change in output. AFC, AVC, AC and MC are undefined at zero output.
Why does MC cut AVC and AC at their lowest points?
An average falls while the next unit costs less than the average, and rises once it costs more. So AVC falls while MC is below it and rises once MC is above it. AC works the same way, but bottoms out at a larger output because AFC keeps falling.
How do you find TFC when TC at zero output is not given?
Use the clue in the question. If AFC at 4 units is Rs 5, TFC = 5 × 4 = 20. If you know TC and TVC at any one output, TFC = TC − TVC. TFC is the same at every output, including zero.
Can marginal product or marginal revenue be negative?
Yes. MP is negative when one more worker lowers total product, so TP is highest just before that. When a firm must cut its price to sell more, MR falls faster than the price and turns negative, so TR is highest just before MR goes below zero.
How do you find the profit-maximising output from a table?
Work out profit (TR − TC) at each output, or compare MR with MC. Profit is highest where MR = MC and MC is rising. If two outputs give the same profit, the firm produces the larger one, where MR equals MC.
When does a firm shut down in the short run?
When the price is below the lowest AVC. Revenue then fails to cover variable cost at every output, so producing loses more than the fixed cost. At zero output the loss is just TFC.
Can each student get different numbers?
Yes. Share with class sends one set to everyone. To print, choose 2 to 30 copies: each student gets a different set with its own code, and the answer keys follow the worksheets.
Sources, checked October 28, 2026: NCERT Introductory Microeconomics, chapter 3, Production and Costs (PDF, reprint 2026-27) and chapter 4, The Theory of the Firm under Perfect Competition (PDF); Cambridge AS and A Level Economics 9708 syllabus 2026 to 2028 (PDF), 7.5 and 7.6.4; AQA AS and A-level Economics specification (PDF), 3.1.3 and 4.1.4; AP Microeconomics Course and Exam Description (PDF), unit 3.