Mastering Exponential Growth & Decay: 8th Grade Quiz

A population of bacteria doubles every 3 hours. If there are initially 500 bacteria, how many will there be after 9 hours?

• 2000

• 1000

• 3000

• 4000

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

• $12,000

• $8,000

• $9,600

• $10,500

A tree grows at a rate of 5% per year. If the tree is currently 10 feet tall, how tall will it be after 4 years?

• 10.5 feet

• 12.16 feet

• 15 feet

• 11 feet

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

• 5 grams

• 20 grams

• 40 grams

• 10 grams

A savings account earns 4% interest compounded annually. If you deposit $1,000, how much will you have in the account after 3 years?

• 1200.00

• 1124.86

• 1000.00

• 1100.00

A population of fish in a lake decreases by 10% each year due to overfishing. If there are currently 1,200 fish, how many will be left after 3 years?

• 874

• 900

• 1,000

• 1,080

A viral video on social media gains 1,000 views every hour. If it starts with 2,500 views, how many views will it have after 5 hours?

• 5000

• 6000

• 7500

• 8000

A certain species of plant grows exponentially, increasing its number by 50% every month. If there are 200 plants now, how many will there be in 3 months?

• 300

• 500

• 675

• 800

A smartphone loses 15% of its value each year. If it was purchased for $800, what will its value be after 3 years?

• $720

• 491.3

• $600

• $350

A town's population is 10,000 and is growing at a rate of 3% per year. What will the population be in 5 years?

• 11000

• 11593

• 12000

• 10500