CAIE IGCSE Mathematics Exponential Growth and Decay

Practise modelling repeated percentage growth or decay, finding unknown rates and determining when a value first crosses a stated threshold.

Exam points

model repeated growth or decay as initial value × (1 ± rate ÷ 100)^time
rearrange the exponential model and take a root to determine an unknown periodic rate
test consecutive whole periods to identify when a population, value or mass first crosses a limit

Covered syllabus points

E1.17.1 Use exponential growth and decay

[Maximum number: 3]

The average attendance increased exponentially by 4% each year for the three years from 2016 to 2019.
In 2019 the average attendance was 1631.
Find the average attendance for 2016.

1450 or 1449 to 1450
M2 for $1631=k\left(1+\frac4{100}\right)^3$ oe
or B1 for $\left(1+\frac4{100}\right)^3$ oe seen
or M1 for $1631=k\left(1+\frac4{100}\right)^n, n>0$ oe

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Covered syllabus points

E1.17 Exponential growth and decay question 1