Test Yourself! practice tool Which of the following are examples of exponential decay? Select all that apply. A vehicle depreciates 13% each year. A tree is doubling in height each year. An investment earns a 5% interest each year. Air pressure decreases 12% for every 1000 meters in height. D The population of a town is growing at an annual rate of 3.5% A retirement account decreases by 12,000 each year. A radioactive element has a decay rate of 10%

## Step 1: <br />Identify the concept of exponential decay. Exponential decay refers to a decrease in a quantity at a rate proportional to its current value. This is often represented by a percentage decrease over time.<br /><br />## Step 2: <br />Apply this concept to each of the given scenarios. <br /><br />### A vehicle depreciates $13\% $ each year: <br />This is an example of exponential decay because the value of the vehicle is decreasing by a certain percentage each year.<br /><br />### A tree is doubling in height each year: <br />This is not an example of exponential decay. In fact, it's an example of exponential growth because the height of the tree is increasing, not decreasing.<br /><br />### An investment earns a $5\% $ interest each year: <br />This is not an example of exponential decay. It's an example of exponential growth because the investment is increasing by a certain percentage each year.<br /><br />### Air pressure decreases $12\% $ for every 1000 meters in height: <br />This is an example of exponential decay because the air pressure is decreasing by a certain percentage for every 1000 meters in height.<br /><br />### The population of a town is growing at an annual rate of $3.5\% $: <br />This is not an example of exponential decay. It's an example of exponential growth because the population is increasing, not decreasing.<br /><br />### A retirement account decreases by $\$ 12,000$ each year: <br />This is not an example of exponential decay. The decrease is a fixed amount, not a percentage of the current value.<br /><br />### A radioactive element has a decay rate of $10\% $: <br />This is an example of exponential decay because the amount of the radioactive element is decreasing by a certain percentage.