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New Zealand
Level 7 - NCEA Level 2

Applications of Exponential Functions (base e)

Interactive practice questions

The population ($P$P) of bacteria in a colony over time ($t$t) is given by $P=e^{0.1t}$P=e0.1t.

Which of the following shows the graph of the population of bacteria over time?

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A

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B

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C

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D
Easy
< 1min

Under certain climatic conditions the proportion $P$P of the current blue-green algae population to the initial population satisfies the equation $P=e^{0.007t}$P=e0.007t, where $t$t is measured in days from when measurement began.

Solve for $t$t, the number of days it takes the initial number of algae to double to the nearest two decimal places.

Easy
4min

The proportion $P$P of the initial mass of a carbon isotope in a dead tree trunk after $t$t years is given by $P=e^{-\frac{\ln2}{5500}t}$P=eln25500t.

The half life is the number of years it takes for the amount of isotope present to drop to half the original amount.

Solve for the half life of this particular isotope.

Easy
2min

The proportion $Q$Q of radium remaining after $t$t years is given by $Q=e^{-kt}$Q=ekt, where $k$k is a constant.

Medium
3min
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Outcomes

M7-2

Display the graphs of linear and non-linear functions and connect the structure of the functions with their graphs

M7-6

Manipulate rational, exponential, and logarithmic algebraic expressions

91257

Apply graphical methods in solving problems

91261

Apply algebraic methods in solving problems

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