Exponential Growth and Decay Quiz
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Questions and Answers

What is the approximate population of Southern right whales after 25 more years if the current population is 38 and it doubles over a 9-year period?

  • 76
  • 114
  • 190
  • 152 (correct)

A weight loss program targets a 10% weight loss each week.

False (B)

How many bacteria will be present after 2 hours if the culture starts with 20 individuals and doubles every 15 minutes?

1280

The half-life of Carbon-14 is approximately _______ years.

<p>6000</p> Signup and view all the answers

Match the following weight loss goals with their corresponding time period:

<p>5% weight loss = Every week 10% weight loss = Every two weeks Maintain weight = Every month Gaining weight = Never</p> Signup and view all the answers

In what year should the population of a developing city, starting at 125,000 in 2005 and growing at 8% per year, reach half a million?

<p>2045 (A)</p> Signup and view all the answers

A bacteria culture doubles every 30 minutes.

<p>False (B)</p> Signup and view all the answers

What is the expected population of a city in 2020 if it grows by 8% yearly starting from 125,000 in 2005?

<p>184224</p> Signup and view all the answers

What is the vertical transformation of the function $y = 1.5^x$ when represented as $y = -2(1.5)^x$?

<p>It reflects over the x-axis and stretches vertically by a factor of 2. (C)</p> Signup and view all the answers

The graph of $y = 1.5^x$ passes through the point (0, 1).

<p>True (A)</p> Signup and view all the answers

What is the base of the exponential function in $y = 1.5^x$?

<p>1.5</p> Signup and view all the answers

In the transformed function $y = -2(1.5)^x$, the coefficient of _____ indicates vertical stretch.

<p>−2</p> Signup and view all the answers

Match the following properties of the functions:

<p>y = 1.5^x = Passes through (0,1) y = -2(1.5)^x = Reflects over x-axis</p> Signup and view all the answers

How much of a radioactive isotope must technicians start with if they need at least 6 grams after 12 minutes and the half-life is 4 minutes?

<p>24 grams (C)</p> Signup and view all the answers

It will take 15 years for there to be 1 tonne of radioactive waste remaining from a 100-tonne stockpile with a half-life of 15 years.

<p>False (B)</p> Signup and view all the answers

How much of the initial population of Canada will remain after 50 years if it decreases by 0.5% per year starting from 34,482,779?

<p>32,665,106</p> Signup and view all the answers

A diver can see ____% of light after diving 60 meters, if the light is halved every 11 meters.

<p>0.35</p> Signup and view all the answers

Match the following radioactive decay examples with their given half-lives:

<p>Radioactive isotope = 4 minutes Radioactive waste = 15 years Lead-210 = 180 years Pension increase = 6% annually</p> Signup and view all the answers

What will the value of a $1000 investment grow to after 4 years at a growth rate of 2.5% per year?

<p>$1104.08 (C)</p> Signup and view all the answers

What will Opa's pension be worth in 10 years if it increases by 6% annually starting from $24,300?

<p>$43,222 (A)</p> Signup and view all the answers

After 1000 years, approximately 30 kg of a 40 kg Lead-210 sample remains.

<p>True (A)</p> Signup and view all the answers

An investment with a 2.4% annual return will double your money in 10 years.

<p>False (B)</p> Signup and view all the answers

How much should you invest now to ensure you have $2000 after 10 years at an interest rate of 2.4%?

<p>$1586.34</p> Signup and view all the answers

What percentage of light remains at a depth of 60 meters if it is halved every 11 meters?

<p>0.35%</p> Signup and view all the answers

Jeremiah's investment account will yield ______ when he turns 25, considering an annual interest rate of 8% compounded semi-annually.

<p>$6767.11</p> Signup and view all the answers

Match the following terms to their definitions:

<p>Compound Interest = Interest calculated on both the initial principal and the accumulated interest from previous periods. Simple Interest = Interest calculated only on the principal amount. Future Value = The amount of money to which an investment will grow over time at a given interest rate. Present Value = Current worth of a future sum of money given a specified rate of return.</p> Signup and view all the answers

Which function is decreasing?

<p>y = -3(2)^x (A)</p> Signup and view all the answers

The expression $y = 2(2)^x + 3$ represents a decreasing function.

<p>False (B)</p> Signup and view all the answers

The annual interest rate of Jeremiah's investment account is _____%.

<p>8</p> Signup and view all the answers

What is the value of $g(x)$ if it is defined as $g(x) = -3(4)$?

<p>-12 (B)</p> Signup and view all the answers

The function $h(x) = -5(!)$ models a negative exponential graph.

<p>True (A)</p> Signup and view all the answers

What is the expected weight of the item mentioned as 12.5 grams?

<p>12.5 grams</p> Signup and view all the answers

The function $f(x) = 5(!)$ represents an exponential function with a base of ______.

<p>5</p> Signup and view all the answers

Match the following values with their respective categories:

<p>$260$ = Whales $1103.81$ = Dollar Amount $43$ = Price $195$ = Time in Minutes</p> Signup and view all the answers

Which of the following is a possible value for $b(x)$ defined as $b(x) = 3(4)$?

<p>24 (A)</p> Signup and view all the answers

The function $h(x) = -5(!)$ ensures the graph is always positive.

<p>False (B)</p> Signup and view all the answers

How many kilograms does the item weigh if $0.85$ kg is mentioned?

<p>0.85 kg</p> Signup and view all the answers

Which function represents the steepest increasing graph?

<p>f(x) = 42x (D)</p> Signup and view all the answers

The function g(x) = 25x is equivalent to r(x) = 52x.

<p>False (B)</p> Signup and view all the answers

What is the general shape of the graph of increasing exponential functions?

<p>An upward sloping curve</p> Signup and view all the answers

The function ____ represents a decreasing exponential graph.

<p>none of the above</p> Signup and view all the answers

Match the following functions with their equivalent forms:

<p>f(x) = 32x g(x) = 25x p(x) = 23x h(x) = 42x</p> Signup and view all the answers

Which of the following pairs of functions are equivalent?

<p>b(x) and g(x) (A)</p> Signup and view all the answers

H(x) = 32x and b(x) = 25x are equivalent graphs.

<p>False (B)</p> Signup and view all the answers

Identify whether the function z(x) = 10x is increasing or decreasing.

<p>increasing</p> Signup and view all the answers

The function p(x) = ____x has a coefficient that necessitates finding its equivalent function.

<p>23</p> Signup and view all the answers

What can be inferred about the functions with lower coefficients?

<p>They rise to infinity at a slower rate than higher coefficients. (D)</p> Signup and view all the answers

Flashcards

Population Doubling

When a population increases to twice its original size over a specific period.

Exponential Growth

Growth that increases at a constantly accelerating rate, often described by a pattern of doubling or multiplying over time.

Exponential Decay

A decrease in quantity that occurs at a steadily decreasing rate, often described by a pattern of halving or dividing over time.

Half-Life

The time it takes for a substance to decay to half its original amount.

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Calculate Future Population

Using an exponential growth model to predict the size of a population at a future point in time.

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Calculate Time for Decay

Using an exponential decay model to determine how long it takes for a substance to decrease to a specific amount.

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Percentage Decrease

A reduction in a value expressed as a proportion of the original value.

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Percentage Increase

An increase in a value expressed as a proportion of the original value.

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Radioactive Decay

The process where a radioactive isotope loses energy by emitting particles, leading to a change in its atomic structure.

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Calculate remaining isotope

To determine the amount of a radioactive isotope left after a certain time, you can use the half-life of the isotope and the elapsed time.

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Population Growth/Decline

The change in the number of individuals in a population over time.

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Percentage Change

The amount of change expressed as a fraction of the original value, multiplied by 100%.

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Sunlight Attenuation

The gradual decrease in the intensity of sunlight as it travels through water.

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Interest Growth

The increase in the value of an investment over time, usually calculated as a percentage of the original investment.

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Compound Interest

Interest calculated not only on the original investment but also on the accumulated interest.

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Principal Amount

The initial amount invested or borrowed, forming the basis for calculating interest.

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Interest Rate

The percentage charged or earned on the principal amount over a period of time.

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Growth Rate

The rate at which an investment increases in value over time.

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Compounding Frequency

How often the interest is calculated and added to the principal.

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Future Value

The value of an investment at a specified future time.

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Present Value

The current value of a future sum of money, discounted at a given interest rate.

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Time Period

The duration of an investment or loan.

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Parent Function

The basic, un-transformed function from which other functions are derived. It's like the original blueprint for other variations.

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Transformation

Changes made to a parent function, affecting its shape, position, or orientation. These changes include shifting, stretching, reflecting, and compressing.

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Vertical Stretch

A transformation that stretches the graph of a function vertically. Multiplying the function by a constant greater than 1 stretches the graph.

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Vertical Reflection

A transformation that flips the graph of a function vertically across the x-axis. Multiplying the function by -1 reflects the graph.

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Vertical Compression

A transformation that compresses the graph of a function vertically. Multiplying the function by a constant between 0 and 1 compresses the graph.

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Exponential Function

A function that involves a base raised to a variable exponent, often used to model growth or decay.

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Base of an Exponential Function

The constant value that is raised to the exponent in an exponential function.

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Exponent of an Exponential Function

The variable that determines the power to which the base is raised in an exponential function.

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Increasing Exponential Function

An exponential function where the output (y-value) increases as the input (x-value) increases. The base is greater than 1.

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Decreasing Exponential Function

An exponential function where the output (y-value) decreases as the input (x-value) increases. The base is between 0 and 1.

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Matching Exponential Graphs

Identifying exponential functions that have the same base and therefore have the same shape on the graph.

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Sketching Exponential Graphs

Drawing the graph of an exponential function based on understanding its increasing or decreasing nature.

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Graphing Exponential Functions

Representing the relationship between input and output values of an exponential function visually.

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What does the base '2' represent in an exponential function?

The base '2' represents a doubling in quantity for each unit of increase in the independent variable (usually time).

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What does the base '0.5' represent in an exponential function?

The base '0.5' represents a halving in quantity for each unit of increase in the independent variable.

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Negative exponent

A negative exponent indicates a reciprocal, meaning the base is flipped and raised to the positive power.

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How to determine if an exponential function represents growth or decay?

An exponential function represents growth if the base is greater than 1, and decay if the base is between 0 and 1.

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Identify the exponential function for the graph

Analyze the graph to determine the base of the exponential function and its initial value. Start with the y-intercept and look for the pattern of increasing/decreasing values.

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Write the exponential function for a graph

Use the general form of an exponential function (y = a*b^x), where 'a' is the initial value, 'b' is the base representing growth or decay, and 'x' is the independent variable.

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Study Notes

Exponential Growth and Decay

  • Whale Population: A Southern right whale population doubled every 9 years. Starting with 38 individuals, the population after 25 more years would be approximately 260 whales.

  • Bacterial Growth: A bacteria culture doubles every 15 minutes. With an initial population of 20, after 2 hours (120 minutes), the population would be 5120. To reach a population of 163 840 would take 195 minutes.

  • Weight Loss Program: If Helene loses 5% of her weight each week, from an initial weight of 280 pounds, she will weigh approximately 151.3 pounds after 12 weeks.

  • City Population Growth: A developing city's population increases by 8% annually. Beginning with 125,000 people in 2005, the population in 2020 is projected to be 260,838 and reach 500,000 people by 2027.

  • Carbon-14 Decay: A fossil of Carbon-14 with an initial weight of 100 grams, and a half-life of 6,000 years, will weigh approximately 12.5 grams after 18,000 years

  • Radioactive Isotope Decay: A radioactive isotope with a 4-minute half-life requires a starting amount of at least 48 grams to have at least 6 grams remaining after 12 minutes.

  • Radioactive Waste: A nuclear power plant has 100 tonnes of radioactive waste with a 15-year half-life. It will take approximately 100 years to reduce the amount of waste to 1 tonne.

  • Canada's Population: With a population decrease of 0.5% per year, Canada's current population of 34,482,779 would be approximately 26,838,379 in 50 years.

  • Sunlight Penetration: Light penetration halves every 11 meters of depth. At 60 meters, only 2.28% of surface light would remain.

Interest

  • Pension Growth: A pension increasing by 6% annually, starting from $24,300. It will be worth $43,517.60 in 10 years.

  • Investment Growth: An investment of $1000 at a 2.5% annual growth rate for 4 years will be worth $1103.81 after that time.

  • Investment Calculation: If you need $2000 after 10 years with an interest rate of 2.4%, the initial investment should be $1577.72.

  • Compound Interest: Jeremiah's grandparents' $3,000 investment, at an 8% annual interest rate compounded semi-annually, will be worth around $21 320.05 when Jeremiah turns 25.

Exponential Functions (Graphs and Transformations)

  • Graphing Exponential Functions: Transformations of parent exponential functions to create new functions.

  • Graphing and Function Definition: Graphing increasing and decreasing exponential functions, along with the function definition.

  • Determining Exponential Function: Finding the function of an exponential graph given the points and characteristics.

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Description

This quiz covers concepts related to exponential growth and decay, including population dynamics, bacterial growth, and transformations of exponential functions. Test your understanding of growth rates, half-lives, and how to model these scenarios mathematically.

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