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Real-World Growth & Decay: Word Problems for 8th Graders

Total questions: 10

Worksheet time: 5mins

Name
Class
Date
1.

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

a)

2000

b)

1000

c)

4000

d)

3000

2.

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)

$14,450

b)

$16,000

c)

$18,500

d)

$17,000

3.

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?

a)

10.5 feet

b)

13.0 feet

c)

15.0 feet

d)

12.16 feet

4.

A savings account earns 4% interest compounded annually. If you deposit $1,000, how much will you have in the account after 5 years?

a)

1500.00

b)

1100.00

c)

1000.00

d)

1216.65

5.

A certain species of fish in a lake decreases by 20% each year due to pollution. If there are currently 1,000 fish, how many will be left after 3 years?

a)

800

b)

400

c)

600

d)

512

6.

A town's population is 10,000 and is growing at a rate of 8% per year. What will the population be in 5 years?

a)

12000

b)

15800

c)

13500

d)

14693

7.

A radioactive substance decays at a rate of 25% per hour. If you start with 80 grams, how much will remain after 2 hours?

a)

60 grams

b)

45 grams

c)

30 grams

d)

20 grams

8.

A smartphone loses 30% of its value each year. If it was purchased for $800, what will its value be after 3 years?

a)

680

b)

400

c)

560

d)

274.4

9.

A certain plant species grows exponentially, doubling in size every month. If it starts at 2 inches, how tall will it be after 6 months?

a)

256 inches

b)

128 inches

c)

64 inches

d)

32 inches

10.

A loan of $5,000 has an interest rate of 6% compounded annually. How much will be owed after 3 years?

a)

$5,500.00

b)

$5,955.08

c)

$6,300.00

d)

$4,800.00