8th Grade Linear Functions as Models Test with Point Values (PDF)

8th Grade math test: Linear Functions as Models – Maths PDF

Sommaire

This linear function models test for 8th Grade covers linear functions as models (Common Core 8.F.B.4, 8.F.B.5), with a free PDF to print.

This 20-point test checks linear functions as models, rate of change, initial value and graph descriptions (Common Core 8.F.B.4 and 8.F.B.5). Work alone, show every step, and write each final answer clearly. You have 45 minutes. Calculators are not needed unless a question says so.

Time and points

About this test

Grade: Grade 8
Chapter: Linear Functions as Models
Standards: 8.F.B.4, 8.F.B.5
Time: 45 minutes
Total: 20 points

Linear function models test: questions

Question 1 – Rate and initial value [3 pts]

Find the rate of change, the initial value, and write the function.

Question 2 – Two points [3 pts]

A linear function passes through $(1, 8)$ and $(4, 17)$. Write its equation.

Question 3 – Interpret [2 pts]

The cost of a school trip is $C = 8n + 40$ dollars for $n$ students. What do 8 and 40 mean?

Question 4 – Describe a graph [3 pts]

Height of an elevator.

Describe the graph: where is it increasing, constant and decreasing?

Question 5 – Model and predict [3 pts]

Battery percent after m minutes.

A game console battery has 60% charge and loses 3 percentage points each minute of play. Write a function and find the charge after 12 minutes.

Question 6 – Table [2 pts]

A table has $x = 2, 4, 6$ and $y = 11, 17, 23$. Is the function linear? If so, write the equation.

Question 7 – Compare [2 pts]

Plan A costs \$20 plus \$6 per month. Plan B costs \$35 plus \$4 per month. Which plan costs less after 12 months?

Question 8 – Linear or not [2 pts]

A graph.

Is this relationship linear? Explain using the rate of change.

Key facts behind this linear function models test

Key facts

Rate of change $m = \frac{\text{change in } y}{\text{change in } x}$; initial value $b$ is $y$ when $x = 0$.
Build a model: find $m$, solve for $b$ with one point, write $y = mx + b$.
A negative rate means the quantity decreases.
A flat segment has rate 0; a curve means the rate is not constant.
Always say what $m$ and $b$ mean in the situation, with units.

How to use this linear function models test

Time yourself: the test is designed for an average student in 45 minutes. Answer the questions you are sure of first, then come back to the longer ones and check your units.

All Grade 8 chapters: Grade 8 math.

Voter.. post

Free printable PDF