Exponential Word Problems

Does the following equation show growth or decay?
y=10,000*1.26^x

• Growth 

• Decay

Does the following equation show growth or decay?
y=10,000*(1-.05)^x

• Growth 

• Decay

Bacteria can multiply at an alarming rate when each bacteria splits into two new cells, thus doubling. If we start with only one bacteria which can double every hour, how many bacteria will we have after half of a day?

• 1024

• 2048

• 8192

• 4096

The population of Hickory NC, can be modeled by P=6191(1.04)t where t is the number of years since 1995. What was the population in 1995?

• 6191

• 1

• 1995

• 1.04

Using logarithms to solve real-world problems: A population of bacteria doubles every 3 hours. If there are 100 bacteria initially, how many will there be after 12 hours?

• 1600

• 1200

• 800

• 200

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?

• 19

• 17

• 38427

• 38425

• 38

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

• $2677.5

• $19361.1

• $3254.52

• $6231