Exponential Growth And Decay SAT

The number of rabbits in a certain population doubles every 40 days. If the population starts with 12 rabbits, which of the following gives the total number of rabbits in the population after t days?

• $12\left(2\right)\left(\frac{t}{40}\right)$

• $12\left(2\right)\left(\frac{40}{t}\right)$

• $12\left(2\right)^{\frac{40}{t}}$

• $12\left(2\right)^{\frac{t}{40}}$

Tags

CCSS.HSF.LE.A.2

Population P of a town is 80,000 this year. If the population of the town decreases at a rate of 4% each year, which of the following expressions gives population P after t years?

• $80,000\left(0.6\right)^t$

• $80,000\left(0.96\right)^t$

• $80,000\left(0.96t\right)$

• $80,000\left(1-0.04t\right)$

Tags

CCSS.HSF.BF.A.2

A house bought ten years ago for $150,000 was sold for $240,000 this year. Which of the following equations can be used to solve the annual growth rate r of the value of the house?

• $240,000=150,000\left(1+\frac{r}{10}\right)$

• $240,000=150,000\left(1+10r\right)$

• $240,000=150,000\left(1+r\right)^{10}$

• $240,000=150,000\left(r\right)^{10}$

Tags

CCSS.HSA.CED.A.1

CCSS.HSF.BF.A.1

CCSS.HSF.LE.A.1

CCSS.HSF.LE.A.2

CCSS.HSF.LE.A.4

A certain radioactive substance has a half-life of 12 days. This means that every 12 days, half of the original amount of substance decays. If there are 128 mg of radioactive substance today, how many mg will be left after 48 days?

• 4

• 8

• 16

• 32

Tags

CCSS.HSF.LE.A.4

Evelyn deposited $3,000 into her bank account, which earns 4% interest annually. She uses the expression  $3,000\left(x\right)^t$  to find the value of the account after t years.

What is the value of x in the expression?

• 1.04

• .04

• 4

• 1.4

Tags

CCSS.HSF.BF.A.2