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9.06 Applications of exponential functions

Interactive practice questions

In a laboratory, the number of bacteria in a petri dish is recorded, and the bacteria are found to triple each hour.

a

Complete the table of values.

Number of hours passed ($x$x) $0$0 $1$1 $2$2 $3$3 $4$4
Number of bacteria ($y$y) $1$1 $\editable{}$ $9$9 $\editable{}$ $\editable{}$
b

If $y$y represents the number of bacteria at time $x$x, which general equation satisfies this model?

$y=a^x$y=ax

A

$y=a^{-x}$y=ax

B
c

Find the equation linking the number of bacteria ($y$y) and the number of hours passed ($x$x).

d

At this rate, how many bacteria will be present in the petri dish after $11$11 hours?

Medium
2min

An initial chemical reaction results in a chain of chemical reactions that follow.

The total number of reactions after $t$t seconds is given by the equation $y=4^t$y=4t.

Medium
3min

The prize of a scratch ticket gives the winner two options:

Option 1: Receive one payment of $\$20000$$20000 immediately, or

Option 2: Receive one dollar on the first day of winnings, double that (two dollars) on the second day, and so on for a month.

Hard
4min

Consider the graph shown.

Hard
2min
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Outcomes

MA11-6

manipulates and solves expressions using the logarithmic and index laws, and uses logarithms and exponential functions to solve practical problems

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