The Life Starter
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Course Library · Lesson 5 of 6
Money · Guided lesson

Test linked assumptions

About 19 minutes · 4 reading + 15 practice and checks
Time includes reading, practice, and questions. Extra videos or further study are optional.
See this course’s project requirements

A fictional twelve-month accrual income forecast with demand/capacity drivers, cost behavior, seasonality, sensitivity and revision log.

Keep your working files in your own notebook or software. Save a private description, checklist, and work link in My Proof.

What to include

  • A feasible-unit and earned-revenue driver ledger.
  • A twelve-month seasonal sales and capacity reconciliation.
  • A cost-behavior and monthly profit bridge.
  • A checked twelve-month income statement with annual bridge.
  • A linked price/demand/cost sensitivity with twelve changed rows.
  • An actual-versus-static/flexible profit bridge and revision log.

Review and revise

Use these criteria to check your work and choose what to improve.

  • Drivers: demand/capacity/price/cost assumptions are explicit.
  • Aggregation: all 12 monthly rows reconcile annual profit.
  • Scenarios: linked changes update rounding/capacity consistently.
  • Evidence: actual/flexible/static bridges and historical revisions remain separate.
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Before you begin

The idea in everyday life

Original fictional practice. All money is USD. No account, payment, personal record or outside participation is required. Original fictional service firm: monthly demand Jan.. Dec=80,90,100,110,120,130,140,150,160,170,180,190. Capacity 150 units/month; units=min(demand, capacity), no inventory/backlog. Each delivered unit earns 40 revenue and 22 variable cost; fixed operating expense 1,800/month and noncash depreciation 100/month. No interest, tax or owner withdrawal modeled. Revenue is earned on delivery, not payment arrival. January actual:90 units, price 38, variable cost 23/unit, fixed 1,800, depreciation 100. Linked price scenario: price 44, demand falls 10% rounded down to whole units, capacity 150; other costs initially fixed.

The idea

Changing price alone can overstate profit when demand also responds.

Follow along

Test linked assumptions — complete worked case

Changing price alone can overstate profit when demand also responds.

Original fictional service firm: monthly demand Jan.. Dec=80,90,100,110,120,130,140,150,160,170,180,190. Capacity 150 units/month; units=min(demand, capacity), no inventory/backlog. Each delivered unit earns 40 revenue and 22 variable cost; fixed operating expense 1,800/month and noncash depreciation 100/month. No interest, tax or owner withdrawal modeled. Revenue is earned on delivery, not payment arrival. January actual:90 units, price 38, variable cost 23/unit, fixed 1,800, depreciation 100. Linked price scenario: price 44, demand falls 10% rounded down to whole units, capacity 150; other costs initially fixed.

Complete monthly drivers

Paste at A1.

AMonthBDemandCCapacityDUnitsERevenueFVariable costGFixed+depreciationHProfit
18015080320017601900-460
29015090360019801900-280
3100150100400022001900-100
411015011044002420190080
5120150120480026401900260
6130150130520028601900440
7140150140560030801900620
8150150150600033001900800
9160150150600033001900800
10170150150600033001900800
11180150150600033001900800
12190150150600033001900800

Copy as plain text
  1. 1. 5.1 Test

    Copy the linked 44 price/10% demand reduction rule and retain baseline.

    You should see: Two linked drivers change.

  2. 2. 5.2 Test

    Round down each reduced demand before applying 150 capacity.

    You should see: Full twelve changed units, total 1,422.

  3. 3. 5.3 Test

    Use 22 contribution and annual 22,800 pool to calculate 8,484.

    You should see: Price gain and volume loss both counted.

  4. 4. 5.4 Test

    Add variable cost 23 in a separate case:21 contribution and 7,062 profit.

    You should see: Scenario dependency log names all changes.

Now change one thing

The linked-price scenario still serves 1,422 units at price 44, but new variable cost is 24 each. Annual fixed cash plus depreciation remains 22,800. Enter operating profit.

Your work

What to finish

A linked price/demand/cost sensitivity with twelve changed rows.

Common mistake

Watch for this

Keeping old volume after the case states a demand response.

How can I tell I understand it?

Verify that your completed linked price/demand/cost sensitivity with twelve changed rows meets the three lesson-specific checks and retains the supporting original records.

Try 3 questions

Quick knowledge check

Answer all 3 questions. Get at least 2 right and the lesson completes automatically.

Not yet passed

You’ll get an explanation for each answer. Signed in? Your results save to your account.

1Under price 44 and variable 22, contribution per unit is what?
2Why recompute volume in the price 44 scenario?
3Variable cost rises 22→23 at 1,422 units; what happens to profit all else fixed?
0 of 3 answeredApply the lesson to a short question, then review the explanation.
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Answer all 3 questions above and get at least 2 right. You can review the explanations and try again.

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Sources and further reading

Explore the references behind this lesson.

Open Stax: Flexible budgets
Source & access notes · checked 2026-10-01

Read static versus actual-volume comparison and interpretation. Original January price/unit-cost decomposition replaces source cases.

Access: Public primary page body opened and relevant sections read through the web reader on 2026-10-01; no account required for reading.

Reuse: Original Life Starter cases, datasets and questions; no source exercise or worked dataset reproduced. Links support further reading.

Open Stax: Operating budgets
Source & access notes · checked 2026-10-01

Read revenue/activity and variable/fixed operating budgets, noncash expense and income-statement assembly; all monthly driver values are original.

Access: Public primary page body opened and relevant sections read through the web reader on 2026-10-01; no account required for reading.

Reuse: Original Life Starter cases, datasets and questions; no source exercise or worked dataset reproduced. Links support further reading.

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