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

Total questions: 10

Worksheet time: 5mins

Name
Class
Date
1.

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

a)

800

b)

100

c)

400

d)

200

2.

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?

a)

600

b)

400

c)

350

d)

488

3.

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?

a)

$12,000

b)

$14,450

c)

$16,000

d)

$17,000

4.

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?

a)

8.05 feet

b)

7.25 feet

c)

10 feet

d)

6.5 feet

5.

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

a)

1100.50

b)

1200.00

c)

1305.25

d)

1157.63

6.

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?

a)

700

b)

800

c)

600

d)

490

7.

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

a)

10500

b)

12167

c)

13000

d)

11500

8.

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

a)

500 grams

b)

250 grams

c)

340.736 grams

d)

400 grams

9.

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?

a)

2.00 meters

b)

5.00 meters

c)

4.50 meters

d)

3.50 meters

10.

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?

a)

600.00

b)

750.00

c)

500.00

d)

669.11