The Life Starter
0 of 6 complete0%
Course Library · Lesson 6 of 6
Life · Guided lesson

Test a model outside its useful range

About 15 minutes · 3 reading + 12 practice and checks
Time includes reading, practice, and questions. Extra videos or further study are optional.
See this course’s project requirements

A linear-model comparison with tables, graphs, slope and intercept interpretations, a solved intersection and a limitation note.

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

What to include

  • Include input/output definitions and bounded domains.
  • Provide checked tables and labeled linear graphs.
  • Interpret rate and starting output with units.
  • Solve an intersection and verify both outputs.
  • Document a capacity-limited model and all changed-case checks.

Review and revise

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

  • Method: applies the course-specific rules to the supplied cases with visible intermediate work.
  • Accuracy: results agree with the stated facts, units, boundaries and independent checks.
  • Reasoning: explains why the result follows and identifies a limitation or unresolved question.
  • Transfer: completes changed cases and revises the final project when a relevant assumption changes.
Open the full course project
Want more background?
Before you begin

The idea in everyday life

Original case: V(t)=10+5t for 0≤t≤6. The container capacity is 40 L, and inflow stops at capacity. Observations at t=0,2,4,6 are 10,20,30,40 L.

The idea

A mathematical rule can be evaluated where its real mechanism no longer works. Distinguish calculation from supported prediction and revise the domain when capacity or a changed process invalidates the model.

Follow along

Test a model outside its useful range — worked practice

A mathematical rule can be evaluated where its real mechanism no longer works. Distinguish calculation from supported prediction and revise the domain when capacity or a changed process invalidates the model.

Original case: V(t)=10+5t for 0≤t≤6. The container capacity is 40 L, and inflow stops at capacity. Observations at t=0,2,4,6 are 10,20,30,40 L.

Case information

Paste at A1.

ARecordBGiven
Original caseOriginal case: V(t)=10+5t for 0≤t≤6. The container capacity is 40 L, and inflow stops at capacity. Observations at t=0,2,4,6 are 10,20,30,40 L.

Copy as plain text
  1. 1. 1. Check supplied observations

    Evaluate the rule at each observed time.

    You should see: 10,20,30,40 L agree with the observations.

  2. 2. 2. Find the limit

    Solve 10+5t=40.

    You should see: t=6 minutes is capacity.

  3. 3. 3. Audit extrapolation

    Calculate the rule at t=8 and compare to the stated mechanism.

    You should see: The formula gives 50 L, exceeding 40 L; continued linear inflow is unsupported.

  4. 4. 4. Write the revised explanation

    State what is known after capacity without inventing extra mechanism.

    You should see: The original linear rule ends at minute six; inflow stops, so the supplied case remains 40 L.

Now change one thing

A tank starts with 12 L, gains 4 L/min and stops at 32 L. When is capacity reached?

Your work

What to finish

A capacity-limited model review with a revised post-limit explanation.

Common mistake

Watch for this

A changed mechanism requires a new rule, not silent continuation.

How can I tell I understand it?

Revise a model when its mechanism changes rather than changing observations to fit it.

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.

1A 30 L tank starts at 6 L and gains 3 L/min. When is it full?
2What distinguishes a checked observation from extrapolation?
3A learner extends the original line past 40 L after inflow stops. What should change?
0 of 3 answeredApply the lesson to a short question, then review the explanation.
6
Finish this lesson

Pass the check. We’ll save the progress.

Answer all 3 questions above and get at least 2 right. You can review the explanations and try again.

Go to the knowledge check
Tools, templates, and lesson sources

Tools and templates

Tools open in a new tab so you can keep your place here.

Sources and further reading

Explore the references behind this lesson.

OpenStax: modeling with linear functions
Source & access notes · checked 2026-10-01

Web open/search showed the official page, its topic heading and relevant concept description. This is a content/source check, not a provider endorsement.

Access: Official page retrieved with the web reader on 2026-10-01; interactive tools and videos were not certified by retrieval.

Reuse: Original fictional teaching cases, calculations, questions and examples; link and short factual paraphrase only. No copied source exercises or illustrations.

Report a problem with this lesson

Tell us what went wrong. Please leave out personal information and private project contents.

No sign-in needed.