IB · Mathematics: Applications & Interpretation SL & HL · Functions

Linear models: IB Mathematics: Applications & Interpretation questions with answers

Free Linear models questions for IB Mathematics: Applications & Interpretation (SL & HL), part of Functions. Each question has the answer and the marking points an examiner would look for.

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Linear models practice questions

Question 1Structured · 7 marksA* challenge

Plan A costs $8 per month plus $5 per GB of data. Plan B costs $35 per month, which includes 10 GB, and $9 for each additional GB.

(a)

Write down the cost of each plan for 8 GB.

[2]
(b)

Write down an expression for the cost of plan B when x > 10.

[1]
(c)

Find the range of values of x for which plan B is cheaper.

[4]
Show answers and mark scheme
PartAnswer and marking pointsMarks
(a)A: $48, B: $35
$48 A1
$35 A1
2
(b)35 + 9(x − 10)
35 + 9(x − 10) A1
1
(c)5.40 < x < 15.8
8 + 5x = 35 (M1)
x = 5.40 A1
8 + 5x = 35 + 9(x − 10) (M1)
5.40 < x < 15.8 A1
4
Question 2Structured · 6 marks

The cost $C of a taxi journey of d km is modelled by C = md + c. A journey of 5 km costs $12.00 and a journey of 17 km costs $33.60.

(a)

Find the value of m and the value of c.

[3]
(b)

Interpret the value of m in this context.

[1]
(c)

Find the greatest distance that can be travelled for $30.

[2]
Show answers and mark scheme
PartAnswer and marking pointsMarks
(a)m = 1.8, c = 3
two equations or gradient from two points (M1)
m = 1.8 A1
c = 3 A1
3
(b)cost per km
each additional km costs $1.80 A1
1
(c)15.0 km
1.8d + 3 = 30 (M1)
15.0 km A1
2
Question 3Structured · 4 marks

A taxi charges a fixed fee of $5 plus $1.5 per kilometre.

(a)

Write down a linear model for the cost C of a journey of d km.

[1]
(b)

A second taxi charges $2 per kilometre with no fixed fee. Find the distance for which both cost the same.

[2]
(c)

State what the gradient of the first model represents.

[1]
Show answers and mark scheme
PartAnswer and marking pointsMarks
(a)C = 1.5d + 5
C = 1.5d + 5 A1
1
(b)10.0 km
equating (M1)
10.0 km A1
2
(c)cost per km
cost per kilometre R1
1
Question 4Structured · 7 marksA* challenge

Plan A costs $10 per month plus $4 per GB of data. Plan B costs $30 per month, which includes 10 GB, and $8 for each additional GB.

(a)

Write down the cost of each plan for 8 GB.

[2]
(b)

Write down an expression for the cost of plan B when x > 10.

[1]
(c)

Find the range of values of x for which plan B is cheaper.

[4]
Show answers and mark scheme
PartAnswer and marking pointsMarks
(a)A: $42, B: $30
$42 A1
$30 A1
2
(b)30 + 8(x − 10)
30 + 8(x − 10) A1
1
(c)5.00 < x < 15.0
10 + 4x = 30 (M1)
x = 5.00 A1
10 + 4x = 30 + 8(x − 10) (M1)
5.00 < x < 15.0 A1
4
Question 5Structured · 6 marks

The cost $C of a taxi journey of d km is modelled by C = md + c. A journey of 8 km costs $18.40 and a journey of 18 km costs $36.40.

(a)

Find the value of m and the value of c.

[3]
(b)

Interpret the value of m in this context.

[1]
(c)

Find the greatest distance that can be travelled for $40.

[2]
Show answers and mark scheme
PartAnswer and marking pointsMarks
(a)m = 1.8, c = 4
two equations or gradient from two points (M1)
m = 1.8 A1
c = 4 A1
3
(b)cost per km
each additional km costs $1.80 A1
1
(c)20.0 km
1.8d + 4 = 40 (M1)
20.0 km A1
2
Question 6Structured · 4 marks

A taxi charges a fixed fee of $3 plus $1.5 per kilometre.

(a)

Write down a linear model for the cost C of a journey of d km.

[1]
(b)

A second taxi charges $2 per kilometre with no fixed fee. Find the distance for which both cost the same.

[2]
(c)

State what the gradient of the first model represents.

[1]
Show answers and mark scheme
PartAnswer and marking pointsMarks
(a)C = 1.5d + 3
C = 1.5d + 3 A1
1
(b)6.00 km
equating (M1)
6.00 km A1
2
(c)cost per km
cost per kilometre R1
1

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Original IB-style practice questions written for mentorriyaz.in. These are not IB past paper questions, and this site is not affiliated with or endorsed by the International Baccalaureate Organization. Updated 2026-11-04. Paper generator · mentorriyaz.in