Exponential Growth & Decay: Fun Math Challenges for 8th Graders

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

• 800

• 100

• 400

• 200

A bacteria culture starts with 200 bacteria and grows at a rate of 25% per hour. How many bacteria will there be after 4 hours?

• 600

• 400

• 350

• 488

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?

• $12,000

• $14,450

• $16,000

• $17,000

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

• 8.05 feet

• 7.25 feet

• 10 feet

• 6.5 feet

A bank account earns 5% interest compounded annually. If you deposit $1,000, how much will you have in the account after 3 years?

• 1100.50

• 1200.00

• 1305.25

• 1157.63

A certain species of fish in a lake decreases by 30% each year due to pollution. If there are currently 1,000 fish, how many will be left after 2 years?

• 700

• 800

• 600

• 490

A town's population is 10,000 and is expected to grow by 4% each year. What will the population be in 5 years?

• 10500

• 12167

• 13000

• 11500

A radioactive substance decays at a rate of 12% per hour. If you start with 500 grams, how much will remain after 3 hours?

• 500 grams

• 250 grams

• 340.736 grams

• 400 grams

A tree is planted at a height of 2 meters and grows at a rate of 15% per year. What will its height be after 4 years?

• 2.00 meters

• 5.00 meters

• 4.50 meters

• 3.50 meters

A savings account has an initial balance of $500 and earns 6% interest compounded annually. How much will be in the account after 5 years?

• 600.00

• 750.00

• 500.00

• 669.11