CAIE IGCSE Mathematics Extended E2.8 Proportion

Covered syllabus points

E2.8.1 Express direct and inverse proportion in algebraic terms and use this

[Maximum number: 3]

y is inversely proportional to $\sqrt{x}$ .
When y=8, x=4.
Find y when x=49.

$2\frac27$ or $\frac{16}{7}$ oe

M2 for $y=\frac{16}{\sqrt{x}}$ or for $y\sqrt{49}=8\sqrt4$ oe.
M1 for $y=\frac{k}{\sqrt{x}}$ .

[Maximum number: 2]

y is inversely proportional to the square of (x+3).
When x=5, y=0.375.
Find y in terms of x.
y=

$y=\frac{24}{(x+3)^2}$ oe final answer
M1 for $y=\frac{k}{(x+3)^2}$

[Maximum number: 3]

y is inversely proportional to the cube root of (x+5).
When x=3, y=12.
Find y when x=22.
y=

8
M1 for $y=\frac{k}{\sqrt[3]{x+5}}$ oe
M1 for substituting their k into $y=\frac{k}{\sqrt[3]{22+5}}$ oe
or M2 for $12\sqrt[3]{3+5}=y\sqrt[3]{22+5}$ oe

All question bank results loaded

CAIE IGCSE Mathematics Extended E2.8 Proportion Topic Practice

Covered syllabus points

Question 1

Question 2

Question 3