Real World Exponential Equations

 Halle deposited $4000 into an account that earns 5% interest each year.  The growth of her investment can be expressed by the exponential equation, A = 4000(1 + .05)^t, where A is the amount in the account after t years.  In how many years will her account exceed $10,000?

• 19 years

• 16 years

• 22 years

• 25 years

• 1.2

• 10

• 0.8

• 100

The equation of an exponential function is given as follows: f(x)=100(1.2)^x . Does this equation represent exponential growth or decay and what is the exponential growth or decay rate?

• Growth, 120%

• Growth, 20%

• Decay, 20%

• Decay, 12%

The equation of an exponential function is given as follows: f\left(x\right)=8\left(0.75\right)^x . Does this equation represent exponential growth or decay and what is the exponential growth or decay rate?

• Growth, 75%

• Growth, 25%

• Decay, 75%

• Decay, 25%

• 19

• 17

• 38427

• 38425

• 38

The function  c(x) = 50 ⋅ (1.08)^x models the cost in dollars, c, of 1 ounce of a certain chemical used in a laboratory.  x represents the number of years since 2005.

How much does an ounce of the chemical cost in 2024?

(round appropriately for the money amount)

• $215.79

• $233.05

• $317.06

• $293.57

The amount of downloads for an album on iTunes, g(d), where d is the number of days since the album was first uploaded can be represented as
g(d) = 5^1.5d
How many downloads will the album have after 3 days?

• 125

• 11

• 1398

• 140

An experiment begins with 20 grams of a radioactive isotope. This isotope has a half-life. If y is the mass in grams remaining after x half-lives have elapsed, which equation represents the amount of grams the isotope will weigh after 4 half-lives?

• 455 wolves

• 455.04007 wolves

• no wolves

• 8360 wolves