Exponential Word Problems

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

During normal breathing, about 12% of the air in the lungs is replaced after one breath. Write an exponential decay model for the amount of the original air left in the lungs if the initial amount of air in the lungs is 500 mL. How much of the original air is present after 24 breaths?

• 22.25

• 23.25

• 24.25

• 25.25

You drink a beverage with 120 mg of caffeine. Each hour, the caffeine in your system decreases by about 12%. How long until you have 10mg of caffeine?

• 16

• 17

• 18

• 19

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

The population of Winnemucca, Nevada, can be modeled by P=6191(1.04)^t where t is the number of years since 1990. What was the population in 1990? 

• 0 people

• It doesn't say

• I don't know

• 6191

The population of Winnemucca, Nevada, can be modeled by P=6191(1.04)^t where t is the number of years since 1990. What percent did the population increase each year?

• 4%

• It doesn't say

• I don't know

• 400%

The population of Bloom Falls, Mass. (population 937) is slowly moving to a bigger city.
Every year the population drops by 4.5%.
What is the multiplier for this problem?

• 1.045 

• .045 

• .955

• 1.955