Mastering Exponential Decay and Half-Life Calculations

A radioactive substance has a half-life of 5 years. If you start with 80 grams, how much will remain after 15 years?

• 20 grams

• 10 grams

• 40 grams

• 5 grams

A certain bacteria culture doubles every hour. If you start with 10 bacteria, how many will there be after 3 hours?

• 80

• 100

• 40

• 20

The population of a town is decreasing at a rate of 10% per year. If the current population is 5000, what will the population be in 5 years?

• 4000

• 2500

• 2952

• 3500

A car's value depreciates by 20% each year. If the car is currently worth $15,000, what will its value be after 3 years?

• $8,400

• $10,000

• $7,680

• $9,600

A certain medication in the bloodstream decreases by 25% every hour. If the initial amount is 200 mg, how much will be left after 4 hours?

• 63.28125 mg

• 50 mg

• 75 mg

• 100 mg

A tree's height decreases by 15% each year due to disease. If the tree is currently 10 meters tall, what will its height be after 2 years?

• 9 meters

• 7.225 meters

• 6.5 meters

• 8.5 meters

A certain type of fish in a lake decreases in population by 30% each year. If there are currently 200 fish, how many will be left after 2 years?

• 80

• 150

• 120

• 98

A radioactive isotope has a half-life of 10 days. If you start with 160 mg, how much will remain after 30 days?

• 10 mg

• 40 mg

• 80 mg

• 20 mg

The amount of a certain chemical in a solution decreases by 40% every hour. If you start with 500 ml, how much will remain after 3 hours?

• 108 ml

• 400 ml

• 250 ml

• 200 ml

A smartphone loses 15% of its value each year. If it was purchased for $800, what will its value be after 4 years?

• $680.00

• $500.00

• $350.25

• $417.61