Exponential Growth and Decay

A population of 1500 deer decreases by 1.5% per year. At the end of 10 years, there will be approximately 1290 deer in the population. Which function can be used to determine the number of deer, y, in this population at the end of t years?

• y = 1500(1 - 0.015)^t
• y = 1500(0.015)^t
• y = 1500(1 + 0.015)^t
• y = 1500(1.5)^t

Tags

TEKS.MATH.A.9C

There were 417 cell phones sold at an electronics store in January. Since then, cell phone sales at this store have increased at a rate of 3.75% per month. At this rate of growth, which function can be used to determine the monthly cell phone sales x months after January?

• f(x) = 417(3.75)^x
• f(x) = 417(0.0375)^x
• f(x) = 417(1.0375)^x
• f(x) = 417(1.375)^x

Tags

TEKS.MATH.A.9C

An antibiotic is introduced into a colony of 12,000 bacteria during a laboratory experiment. The colony is decreasing by 14.9% per minute. Which function can be used to model the number of bacteria in the colony after x minutes?

• f(x) = 12000(1 + 14.9)^x
• f(x) = 12000(1 - 14.9)^x
• f(x) = 12000(1 + 0.149)^x
• f(x) = 12000(1 - 0.149)^x

Tags

TEKS.MATH.A.9C

Some banks charge a fee for a savings account that is left inactive for an extended period of time. The equation y = 5000(0.98)^x represents the amount remaining, y, of one account that was left inactive for a period of x years. What does the number 5000 represent in this situation?

• A fee charged for an inactive account
• The percent of money in the account after x years
• The amount of money in the account initially
• The amount of money in the account after x years

Tags

TEKS.MATH.A.9B

A child asks her dad for an allowance that starts with a penny and then doubles every day for a month. Which function can be used to model the amount of money, A, the child will receive each day, x?

• A(x) = 2(0.01)^x
• A(x) = 0.01(2)^x
• A(x) = 0.01(1 - 2)^x
• A(x) = 2(1.01)^x

Tags

CCSS.HSF.LE.A.2

Which of the following functions shows an initial amount of $15 and an increase of 35% each year?

• y = 15(35)^x
• y = 15(1.35)^x
• y = 15(0.35)^x
• y = 35(1.15)^x

Tags

CCSS.HSF.LE.A.2

Write an equation that models the following situation:
Samantha's hair was known to grow very rapidly. It began at a length of 6 in and grew at a rate of 14% a week.

• y=6(0.14)^x
• y=6(1+14)^x
• y=6(1.14)^x
• y=6(0.86)^x

Tags

CCSS.HSF.LE.A.2

Suppose a culture of bacteria begins with 5000 cells and dies by 30% each year. Write an equation that represents this situation.

• y=5000(0.7)^x
• y=30(5000)^x
• y=5000(1.3)^x
• y=5000x^x

Tags

CCSS.HSF.LE.A.2

The original value of a painting is $1400, and the value increases by 9% each year. Write an exponential growth function to model this situation.

• y=1400(1.09)^x
• y=1.09(1400)^x
• y=1400(.91)^x
• y=1.09^x

Tags

TEKS.MATH.A.9C

A 78 gram sample of Uranium loses half of its mass each year.  What is the exponential equation? 

• y=78(0.5)^x
• y=78(1.5)^x
• y=78(2)^x

Tags

CCSS.HSF.LE.A.2