Real-World Growth and Decay Problems for 8th Graders

A population of rabbits doubles every year. If there are currently 50 rabbits, how many will there be in 3 years?

• 100

• 200

• 800

• 400

A car's value decreases by 15% each year. If the car is currently worth $20,000, what will its value be after 2 years?

• $18,000

• $14,450

• $16,000

• $12,000

A bacteria culture grows by 25% every hour. If there are initially 200 bacteria, how many will there be after 4 hours?

• 390

• 400

• 300

• 250

A tree grows at a rate of 3 inches per year. If it is currently 10 feet tall, how tall will it be in 5 years?

• 12 feet

• 9.5 feet

• 10.5 feet

• 11.25 feet

A certain investment grows at a rate of 5% per year. If you invest $1,000, how much will it be worth after 4 years?

• 1100.00

• 1215.51

• 1000.00

• 1500.00

A radioactive substance decays at a rate of 10% per hour. If you start with 500 grams, how much will remain after 3 hours?

• 450 grams

• 364.5 grams

• 300 grams

• 500 grams

A savings account earns 4% interest compounded annually. If you deposit $1,500, how much will you have after 5 years?

• 2000.00

• 1750.50

• 1500.00

• 1824.98

A population of fish decreases by 20% each year due to overfishing. If there are currently 1,000 fish, how many will be left after 2 years?

• 500

• 800

• 640

• 720

A tree's height is measured at 15 feet and it grows at a rate of 2 feet per year. What will its height be in 10 years?

• 30 feet

• 25 feet

• 35 feet

• 40 feet

A certain type of mold grows at a rate of 30% per day. If you start with 100 grams, how much will you have after 3 days?

• 300 grams

• 180 grams

• 219.7 grams

• 150 grams