Exponential Growth: Doubling Time Challenges for 8th Graders

A bacteria culture doubles in size every 3 hours. If the initial population is 500, how many bacteria will there be after 9 hours?

• 1000

• 2000

• 4000

• 3000

A tree grows at a rate of doubling its height every year. If it is currently 2 meters tall, how tall will it be after 4 years?

• 16 meters

• 4 meters

• 8 meters

• 32 meters

A certain investment triples in value every 5 years. If you invest $1,000, how much will it be worth after 15 years?

• 27000

• 45000

• 9000

• 15000

A viral video on social media gains 1,000 views in the first hour and then doubles its views every hour. How many views will it have after 5 hours?

• 16000

• 32000

• 40000

• 24000

A population of rabbits triples every year. If there are currently 20 rabbits, how many will there be after 2 years?

• 180

• 240

• 60

• 100

A certain type of plant doubles in height every month. If it is currently 10 cm tall, what will its height be after 6 months?

• 20 cm

• 80 cm

• 160 cm

• 640 cm

A savings account earns interest that doubles the balance every 10 years. If you start with $500, how much will you have after 30 years?

• $2000

• $4000

• $1000

• $8000

A computer virus spreads by doubling the number of infected computers every day. If there are 10 infected computers today, how many will there be in 4 days?

• 320

• 80

• 240

• 160

A certain species of fish triples in population every 2 years. If there are currently 50 fish, how many will there be after 6 years?

• 900

• 1350

• 600

• 1000

A new video game sells 1,000 copies in its first week and then doubles its sales every week. How many copies will it sell after 4 weeks?

• 5000

• 20000

• 12000

• 15000