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2.04 Modelling linear relationships

Worksheet
Linear relationships from tables
1

A dam used to supply water to the neighboring town had the following data recorded for its volume over a number of months:

\text{Month }(M)1234
\text{Volume in billions of litres } (V)11210611080
a

Plot the points on the number plane.

b

Is this relationship linear?

2

Chirping crickets can be used as an indication of how hot or cool it is outside. Different species of crickets have different chirping rates but for a particular species the following data was recorded:

\text{Number of chirps per minute } (x)80110140160
\text{Temperature } (y \ \degree \text{C})16192224
a

Graph the linear relationship represented in the table.

b

Determine the temperature when the crickets make 130 chirps each minute.

c

How many chirps per minute will the crickets make if the temperature is 27\degree\text{C}?

d

How many chirps per minute will the crickets make if the temperature is 20\degree\text{C}?

3

A diver starts at the surface of the water and begins to descend below the surface at a constant rate. The table below shows the depth of the diver over 4 minutes:

\text{Number of minutes passed } (x)01234
\text{Depth of diver in metres } (y)00.81.62.43.2
a

Graph the linear relationship represented in the table.

b

Calculate the increase in depth each minute.

c

Calculate the depth of the diver after 24 minutes.

4

Petrol costs a certain amount per litre. The table shows the cost of various amounts of petrol in dollars:

\text{Number of litres }(x)010203040
\text{Cost of petrol }(y)016.4032.8049.2065.60
a

Find the cost of petrol per litre.

b

Write an equation linking the number of litres of petrol pumped \left(x\right) and the cost of the petrol \left(y\right).

c

Explain the meaning of the gradient in this context.

d

Calculate the cost of 47 \text{ L} petrol.

5

The time in minutes and the temperature in degrees Celsius (\degree \text{C}) are given in the following table:

\text{Time } (x)12345
\text{Temperature } (y\degree \text{C})813182328
a

By how much is the temperature increasing each minute?

b

Find the initial temperature.

c

Form an equation relating x and y.

d

Graph the linear relationship represented in the table.

6

Petrol costs a certain amount per litre. The table shows the cost of various amounts of petrol in dollars:

\text{Number of litres }(x)010203040
\text{Cost of petrol }(y)012243648
a

Graph the linear relationship represented in the table.

b

Find the cost of petrol per litre.

c

Calculate the cost of 75 \text{ L} petrol.

7

Consider the following table that shows the temperature of a metal plate, in \degreeC, after an amount of time, measured in minutes:

\text{Time }(x)12345
\text{Temperature }(y)1015202530
a

Graph the linear relationship represented in the table.

b

By how much is the temperature increasing each minute?

c

Find the initial temperature.

d

Form an equation relating x and y.

8

After Sally starts running, her heartbeat increases at a constant rate as shown the following table:

\text{Number of minutes passed } (x)024681011
\text{Heart rate } (y)7581879399105
a

Complete the table.

b

Graph the linear relationship represented in the table.

c

By how much is her heartbeat increasing each minute?

9

Emma is gathering data on the growth of her plant as shown in the following table:

\text{Day } (d)2468
\text{Height of plant } (h \text{ cm})6101418
a

Graph the linear relationship represented in the table.

b

How tall was the plant when Emma started tracking the growth?

c

Determine the height of the plant on day 12.

d

On which day will the plant be 18 \text{ cm} tall?

e

Write a linear equation to represent the height, h, as a function of the day, d.

10

When a plane is coming in to land, the pilot requires the plane to lose altitude at a rate of 5\text{ m/s}. At the beginning of a particular descent the plane starts at an altitude of 8500\text{ m}. The altitude of the plane at various times since starting descent are shown in the following table:

\text{Descent } (t\text{ seconds})02004001600
\text{ Altitude } (A)850075006500500
a

Graph the linear relationship represented in the table.

b

Determine the altitude of the plane 500 seconds since starting the descent.

c

How many seconds did the plane take to descend to the ground?

d

Write a linear equation to represent the altitude of the plane, A, as a function of the number of seconds since commencing descent, t.

11

Katrina is going to catch a taxi into the city. She knows that the taxi has a flat fee of \$0.30 and that the fare rises by \$0.10 per kilometre travelled. The fares for particular distances are shown in the following table:

\text{Distance travelled } (d \text { km})6789
\text{Fare } (F)0.901.001.101.20
a

Graph the linear relationship represented in the table.

b

Write a linear equation to represent the fare, F, as a function of the journey's length, d.

c

Calculate the fare for a 14 \text{ km} journey.

d

Find the distance travelled for a trip that costs \$0.60.

12

Justin is looking into the details of his mobile phone plan. He knows the costs for several call lengths as shown in the table:

\text{Length of call in minutes } (t)261014
\text{Cost } (C)\$1.00\$2.20\$3.40\$4.60
a

Plot the given data on a number plane and connect the points with a line.

b

How much will it cost to make an 8-minute call?

c

Find the length of a call that costs \$1.60.

d

Determine the rule that connects the cost of a call, C, to the length of the call, t.

Linear relationships from information
13

Beth’s income is based solely on the number of hours she works, and she is paid a fixed hourly wage. She earns \$750 for working 30 hours. Let y represent Beth’s income after working x hours.

a

Sketch a graph that displays her income against her hours worked.

b

Form an equation relating x and y.

c

Calculate Beth's income when she works 25 hours.

d

Calculate the number of hours that Beth must work to earn \$125.

14

The cost, y, for a business to operate, can be expressed in terms of x, the total number of hours it has operated for. The cost is \$150 an hour.

a

Sketch a graph that displays the cost against time.

b

Form an equation relating x and y.

c

Find the total cost for the business to operate for 22 hours.

d

Find the number of hours that the business needs to operate to incur a total cost of \$5400.

15

A baseball is thrown vertically upward, and the velocity of the baseball, V in metres per second after T seconds is given by V = 120 - 32 T.

a

Complete the following table of values:

\text{Time } (T)01234
\text{ Velocity } (V)
b

Graph the linear relationship represented in the table.

c

What does the negative value of V, when T = 4, mean in context?

d

Discuss the usefulness and limitations of this model.

16

A racing car starts the race with 250 litres of fuel. From there, it uses fuel at a rate of 5 litres per minute.

a

Complete the table of values:

\text{Number of minutes passed, }x0510152050
\text{Amount of fuel left in tank, }y
b

Determine an algebraic rule linking the number of minutes passed, x, and the amount of fuel left in the tank, y.

c

Describe how the amount of fuel in the car is changing over time.

d

Discuss the usefulness and limitations of this model.

Gradient and vertical intercept
17

The cost, y, for a business to operate, can be expressed in terms of x, the total number of hours it has operated for. The cost is \$120 an hour.

a

Sketch a graph that displays the cost against time.

b

State the gradient of the line.

c

Form an equation relating x and y.

d

Find the total cost for the business to operate for 28 hours.

e

Find the number of hours that the business needs to operate to incur a total cost of \$3840.

18

The table shows Peter's earnings from ironing shirts:

Shirts sewed02468
Earnings48121620
a

Sketch the graph that depicts his earnings in dollars (y) against the number of shirts he irons (x).

b

Calculate the gradient of the line.

c

What does the gradient represent in this context?

d

What is the y-intercept of the line?

e

What does the y-intercept represent in this context?

f

What will be his total earnings if he irons a total of 14 shirts?

g

How many shirts will he have to iron in order to earn \$28?

19

A ball is rolled down a hill. The table below shows the velocity, in \text{m}/\text{s} of the ball after a given number of seconds:

\text{Time in seconds, }t012345
\text{Velocity, }V1819.721.423.124.826.5
a

Determine the rule that connects the velocity, V, to the time in seconds, t.

b

Graph the line that represents the relationship between velocity and time.

c

Calculate the gradient of the line.

d

Explain the meaning of the gradient of the line in this context.

e

Calculate the vertical intercept of the line.

f

Explain the meaning of the vertical intercept of the line in this context.

g

Find the velocity of the ball after 17 seconds, rounded to one decimal place.

h

Discuss the usefulness and limitations of this model.

20

The number of fish in a river is approximated over a five year period. The results are shown in the table below:

\text{Time in years }(t)012345
\text{Number of fish }(F)600057005400510048004500
a

Sketch the graph of the relationship on a number plane.

b

Calculate the gradient of the line.

c

What does the gradient represent in this context?

d

State the value of F when the line crosses the vertical axis.

e

Write an algebraic equation for the line relating t and F.

f

Hence determine the number of fish remaining in the river after 9 years.

g

Determine the number of years it takes for there to be 1800 fish remaining in the river.

21

Valentina left for a road trip at midday. The graph shows the total distance travelled (in kilometres) t hours after midday.

Let the horizontal axis represent the time in hours and the vertical axis represent the distance travelled in kilometers.

a

State the gradient of the line.

b

Explain the meaning of the gradient in this context.

1
2
3
4
5
t
115
230
345
460
575
\text{Distance (km)}
22

The graph shows the temperature of a room after the heater has been turned on:

a

State the gradient of the line.

b

State the y-intercept.

c

Write an equation to represent the temperature of the room, y, as a function of time, t.

d

Explain the meaning of the gradient in this context.

e

Explain the meaning of the y-intercept in this context.

f

Find the temperature of the room after the heater has been turned on for 30 minutes.

g

Discuss the usefulness and limitations of this model.

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9
t\text{ (mins)}
1
2
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8
9
\text{Temp (}\degree \text{C)}
23

The graph shows the amount of water remaining in a bucket that was initially full before a hole was made in it's side.

a

State the gradient of the line.

b

Find the y-intercept.

c

Write an equation to represent the amount of water remaining in the bucket, y, as a function of time, x.

d

Explain the meaning of the gradient in this context.

e

What does the y-intercept represent in this context?

f

Find the amount of water remaining in the bucket after 54 minutes.

5
10
15
20
25
30
35
\text{Time (mins)}
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
\text{Water (L)}
24

The table shows the linear relationship between the number of plastic chairs manufactured, x, and the total manufacturing cost, y:

Number of plastic chairs51015
Cost (dollars)135185235
a

State the gradient of the line.

b

Form an equation relating x and y.

c

Find the y-intercept.

d

Explain the meaning of the y-intercept in this context.

e

Explain the meaning of the gradient of the function in this context.

f

Find the total cost of manufacturing 25 plastic chairs.

Conversion graphs
25

The graph shows the conversion between Country A and Country B's currency:

a

Use the graph to convert 8 of currency A to currency B.

b

Use the graph to convert 2 of currency B to currency A.

c

Discuss the usefulness and limitations of this model.

1
2
3
4
5
6
7
8
9
10
\text{B}
2
4
6
8
10
12
14
16
18
\text{A}
26

The graph shows the conversion between miles and kilometres:

a

Convert 10 miles to kilometres.

b

Hence, how many kilometres is 1 mile equal to?

1
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9
10
\text{mi}
2
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8
10
12
14
16
18
\text{km}
27

The graph shows the conversion between temperatures in Celsius and Fahrenheit:

-20
-10
10
20
30
40
50
60
70
80
90
100
\degree{F}
-50
-40
-30
-20
-10
10
20
30
40
50
\degree{C}

Use the graph to convert the following as indicated:

a

40 \degree\text{C} to Fahrenheit.

b

50 \degree\text{F} to Celsius.

c

- 20 \degree\text{F} to Celsius.

28

The graph shows the conversion between temperatures in Celsius and Fahrenheit:

a

Use the graph to convert 10 \degree \text{C} into Fahrenheit.

b

0 \degree \text{C} is 32 \degree \text{F}. Hence, for every 1 \degree \text{C} increase, by how much does the Fahrenheit temperature increase?

c

Would 80 \degree \text{F} be above or below normal body temperature? Normal body temperature is approximately 37 \degree \text{C}.

d

Write the rule for conversion between Celsius \left(\text{C}\right) and Fahrenheit \left(\text{F}\right).

e

Convert 35 \degree \text{C} into Fahrenheit.

5
10
15
20
25
30
35
40
\degree \text{C}
10
20
30
40
50
60
70
80
90
100
\degree \text{F}
29

The graph shows the conversion between miles and kilometres:

a

If a car is driving 32 \text{ km/hr} in a school zone, at what speed are they travelling in miles per hour?

b

A road sign states the speed limit to be 128\text{ km/hr}. Calculate this speed limit in miles per hour.

4
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16
20
24
28
32
36
\text{km}
2
4
6
8
10
12
14
16
18
20
22
\text{mi}
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Outcomes

MS11-1

uses algebraic and graphical techniques to compare alternative solutions to contextual problems

MS11-2

represents information in symbolic, graphical and tabular form

MS11-6

makes predictions about everyday situations based on simple mathematical models

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