Mastering Exponential Growth and Decay: Grade 8 Quiz

A population of 500 rabbits increases by 20% each year. How many rabbits will there be after 3 years?

• 1000

• 720

• 864

• 600

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

• $16,000

• $14,450

• $18,000

A bacteria culture starts with 1,000 bacteria and doubles every 4 hours. How many bacteria will there be after 12 hours?

• 4000

• 2000

• 8000

• 16000

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

• 15 feet

• 8 feet

• 10 feet

• 12.76 feet

A radioactive substance decays at a rate of 10% per hour. If you start with 200 grams, how much will remain after 3 hours?

• 180 grams

• 145.8 grams

• 220 grams

• 100 grams

A savings account has an initial deposit of $1,000 and earns 6% interest compounded annually. How much will be in the account after 4 years?

• $1,100.00

• $1,500.00

• $1,200.00

• $1,262.48

A certain species of fish decreases in population by 25% each year due to overfishing. If the current population is 800, what will the population be in 2 years?

• 500

• 300

• 450

• 600

A smartphone loses 30% of its value as soon as it is purchased. If the original price was $800, what is its value after the first year?

• $560

• $640

• $480

• $720

A tree's height is 15 feet and it grows at a rate of 4% per year. What will its height be after 3 years?

• 16.87 feet

• 15.60 feet

• 17.20 feet

• 14.50 feet

A certain type of mold grows at a rate of 50% every day. If you start with 10 grams, how much will you have after 5 days?

• 75.94 grams

• 50 grams

• 100 grams

• 30 grams