Real-World Exponential Growth and Decay Problems

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

• 40 grams

• 20 grams

• 10 grams

• 5 grams

A population of bacteria doubles every 3 hours. If you start with 500 bacteria, how many will there be after 12 hours?

• 4000

• 8000

• 16000

• 1000

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

• $5,000

• $10,000

• $12,000

• $7,680

A certain species of fish decreases in population by 10% each year. If there are currently 1,200 fish, how many will be left after 4 years?

• 787

• 1000

• 600

• 900

A tree grows at a rate of 5% per year. If the tree is currently 10 feet tall, how tall will it be after 2 years?

• 12 feet

• 9.5 feet

• 11.025 feet

• 10.5 feet

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

• 100 mg

• 63.28 mg

• 150 mg

• 50 mg

A bank account earns 6% interest compounded annually. If you deposit $1,000, how much will you have after 5 years?

• 1200.00

• 1000.00

• 1338.23

• 1500.00

A certain type of mold grows exponentially, doubling in size every 2 days. If you start with 10 grams, how much will you have after 10 days?

• 100 grams

• 640 grams

• 250 grams

• 320 grams

A car depreciates in value by 15% each year. If the car was purchased for $20,000, what will its value be after 2 years?

• $14,450

• $18,000

• $12,000

• $16,000

A certain radioactive isotope has a half-life of 10 years. If you have 50 mg of the isotope, how much will remain after 30 years?

• 6.25 mg

• 3.125 mg

• 25 mg

• 12.5 mg