Free Printable Writing exponential growth or decay functions

1.

Write the exponential function for :

A population of beetles that starts at 50 increases by 65% each year.

a)

$f\left(x\right)\ =\ 50\ \left(.65\right)^x$

b)

$f\left(x\right)=\ 50\left(1.65\right)^x$

c)

$f\left(x\right)\ =\ 65\left(.50\right)^x$

d)

$f\left(x\right)=\ 50\left(.35\right)^x$

2.

Write the exponential function for :

Your heart rate reaches 58 bpm and then increases by 20% each minute.

a)

$f\left(x\right)\ =\ 58\ \left(.20\right)^x$

b)

$f\left(x\right)=\ 58\left(1.20\right)^x$

c)

$f\left(x\right)\ =\ 20\left(.58\right)^x$

d)

$f\left(x\right)=\ 58\left(.80\right)^x$

3.

Write the exponential function for :

An account with $25,000 decreases in value 9% each year.

a)

$f\left(x\right)\ =\ 25,000\left(.90\right)^x$

b)

$f\left(x\right)=25,\ 000\left(0.09\right)^x$

c)

$f\left(x\right)\ =\ 25,000\left(.91\right)^x$

d)

$f\left(x\right)=\ 25,000\left(1.09\right)^x$

4.

Write the exponential function for :

A new car you bought for $48,000 decreases in value 10% each year.

a)

$f\left(x\right)\ =48,000\left(.90\right)^x$

b)

$f\left(x\right)=48,000\left(0.10\right)^x$

c)

$f\left(x\right)\ =48,000\left(1.10\right)^x$

d)

$f\left(x\right)=48,000\left(1.01\right)^x$

5.

Alex invests in a savings account that pays 3.50% interest increases quarterly. What is the decay/growth factor?

a)

$100\ \%\ +\ 3.50\ \%\$

b)

$100\%\ -3.50\%$

c)

$100\ \%\ \cdot\ 3.50\ \%$

d)

$100\%\ \div3.50\%$

6.

Alex invests in a savings account that increases by 3.50% quarterly. What is the growth/decay factor?

a)

1350%= 13.50

b)

96.5% = .965

c)

103.50% = 1.035

d)

10.35%= .1035

7.

To write the exponential function for :

A population of beetles that starts at 50 increases by 65% each year.

What is the 1st step?

a)

Add $100+\ 65\%$

b)

Subtract $100-65\%$

c)

change the $65\ \%$ to a decimal by moving it two units to the left

d)

change the $65\ \%$ to a decimal by moving it two units to the righy

8.

In an exponential function, to have an increase of 15% you have do the following:

(select 2)

a)

$Add\ \ \ \ \ \ 100\%\ +\ 15\%\ \ \$

b)

Change 115% to a decimal which is 1.15

c)

$Subtract\ \ \ \ 100\%\ -15\%$

d)

Change 85% to a decimal which is 0.85

9.

To write the exponential function for :

An account with $25,000 decreases in value 9% each year.

What is the 1st step?

a)

Add $100+\ 9\%$

b)

Subtract $100-9\%$

c)

change the $9\ \%$ to a decimal by moving it two units to the left

d)

change the $9\%$ to a decimal by moving it two units to the right

10.

In an exponential function, to have an decrease of 9% you have do the following:

(select 2)

a)

$Add\ \ \ \ \ \ 100\%\ +\ 9\%\ \ \$

b)

Change 109% to a decimal which is 1.09

c)

$Subtract\ \ \ \ 100\%\ -9\%$

d)

Change 91% to a decimal which is 0.91

11.

When you have a percentage increase you have to:

a)

Add $100\ +\ \%$

b)

Subtract $100-\%$

c)

$Multiply\ \ \ \ \ \ 100\cdot\ \%$

d)

Divide $100\div\%$

12.

When you have a percentage decrease you have to:

a)

Add $100\ +\ \%$

b)

Subtract $100-\%$

c)

$Multiply\ \ \ \ \ \ 100\cdot\ \%$

d)

Divide $100\div\%$

Writing exponential growth or decay functions

Total questions: 12

Worksheet time: 9mins

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