CAIE IGCSE Mathematics Using Exponential Growth and Decay

Practise applying repeated growth and decay multipliers to populations, values and masses and solving for a missing rate or number of periods.

Exam points

calculate a future value with initial value × growth or decay multiplier raised to time
divide by the initial value and take a time root to recover the periodic multiplier or rate
compare consecutive integer times to find the first whole period above or below a target

[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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E1.17.1 Use exponential growth and decay question 1