Exponential Growth and Decay Word Problems

Middletown High School has student elections every year. Lately, the school has seen a 5% decrease in voting from election to election. If 910 students voted this year, how many will be expected to vote 8 years from now? (Round to the nearest whole number if necessary).

• 604

• 777

• 29

• 198

Tags

CCSS.HSF-LE.A.1C

Jenny has $20 in a savings account. The interest rate is 5%, compounded annually. To the nearest cent, how much interest will she earn in 2 years?

• $2.05

• $45.79

• $1.99

• $7.51

Tags

CCSS.HSF.BF.A.2

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%

Tags

CCSS.HSF-LE.A.1C

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 240 breaths?

• Just about zero mL
• 60 mL
• 440 mL
• 0 mL

Tags

CCSS.HSA.CED.A.1

CCSS.HSF.LE.A.1

CCSS.HSF.LE.A.2

CCSS.HSF.BF.A.1

CCSS.HSF.LE.B.5

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? 

• 19 to 20 hours
• 10 to 20 hours
• 15 to 16 hours
• 5 to 6 hours

Tags

CCSS.HSF.LE.A.4

The foundation of your house has about 1,200 termites. The termites grow at a rate of about 2.4% per day. How long until the number of termites doubles?

• 29 to 30 years
• 23 to 24years
• 15 to 16 years
• 19 to 20 years

Tags

CCSS.HSF.LE.A.4

In the formula y = a(1±r)^t, what does the "a" represent?

• The total after the increase or decrease

• The initial amount

• The Rate of Change

• The number of times the change has happened over time

Tags

CCSS.HSF-IF.C.8B

Classify the model as Exponential GROWTH or DECAY.
A=1200(.85)⁶

• Growth
• Decay

Tags

CCSS.HSF-IF.C.8B

If 10 mg of iodine 131 is given to a patient, how much is left after 24 days? The half-life of iodine-131 is 8 days.

• 1.25mg
• 1.25g
• 10g
• 10mg

Tags

CCSS.HSF.LE.A.4

The half-life of strontium-90 is 25 years. How much strontium-90 will remain after 100 years if the initial amount is 4.0 g?

• 3.0g
• 0.25mg
• 0.3g
• 0.25g

Tags

CCSS.HSF.LE.A.4