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Standard Level

2.03 Direct variation

Worksheet
Direct variation
1

If \left(4, 512\right) is on the curve, P = k Q^{4}, solve for k.

2

A variable M is directly proportional to the square of N.

a

Using k as the constant of proportionality, form an equation for M in terms of N.

b

Given that \left(4, 64\right) satisfies the equation, solve for k.

3

Consider the relationship where y is directly proportional to the cube of x.

a

Using k as a constant of proportionality, state the equation relating x and y.

b

The following table of values shows the relationship between x and y:

x12345
y32481192375

Solve for k, the constant of proportionality.

4

y is a power function which is directly proportional to x^{n}.

a

Using k as the proportionality constant, form an equation for y in terms of x.

b

The table below shows values that satisfy the relationship y = k x^{n}, for the case when n = 2.

x246810
y32128288512800

Solve for the constant of proportionality k. Round your answer to the nearest integer.

5

y is a power function which is directly proportional to x^{n}.

a

Using k as the proportionality constant, form an equation for y in terms of x.

b

The table below shows values that satisfy the relationship y = k x^{n}, for the case when n = 3.

x246810
y-48-384-1296-3072-6000

Solve for the constant of proportionality k. Round your answer to the nearest integer.

6

For the quadratic function pictured here, determine the constant of proportionality k:

-4
-3
-2
-1
1
2
3
4
x
-4
-3
-2
-1
1
2
3
4
y
7

For the quadratic shown, determine the constant of proportionality k:

-4
-3
-2
-1
1
2
3
4
x
-4
-3
-2
-1
1
2
3
4
y
8

The following graph shows the intersection of the two functions y = m x^{\frac{4}{3}} and y = k x^{\frac{1}{3}}:

a

Find the value of m.

b

Find the value of k.

1
2
3
4
5
6
7
8
9
x
1
2
3
4
5
6
7
8
9
y
Applications
9

In exchange rate calculations the constant of proportionality is the exchange rate itself. Determine the exchange rate, k, if someone can purchase:

a

889.00 AUD with 700.00 USD.

b

553.00 USD with 700.00 AUD.

10

The heart mass H of a mammal is proportional to its body mass M.

a

Using k as the constant of proportionality, form an equation relating H and M.

b

Given that a human with a body mass of 77kg has a heart mass of 0.462kg, determine k, the constant of proportionality.

c

If a Chimpanzee has a body mass of 57kg, what is the heart mass H?

d

If a Macaque has a heart mass of 0.084kg, solve for its body mass M.

11

The blood circulation time C of a mammal is proportional to the fourth root of its body mass B.

a

Using k as the constant of proportionality, form an equation relating C and B.

b

Given that an elephant with a body mass of 5290\text{ kg} has a blood circulation time of 148 seconds, determine k, the constant of proportionality. Round your answer to one decimal place.

c

If a Orangutang has a body mass of 40\text{ kg}, find C, its circulation time. Round your answer to one decimal place.

d

If a Squirrel has a circulation time of 22 seconds, what is the body mass? Round your answer to one decimal place.

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