Exponential growth and decay

Grade 9 Math Worksheet

NameDate

Circle the best answer, or write your answer on the line.

  1. Esme's school robotics club grows by 12% each year. What number goes on each arrow of the growth table?

  2. Each wash fades the dye in Jun's shirt by 6%. What number goes on each arrow of the growth table?

  3. Noah looks up a used bike worth $360. Its value drops 15% each year. To the nearest dollar, what is it worth after 4 years?

  4. Zee's notes say the light through t layers of film is y = 1200(0.85)^t. By what percent does the light drop with each layer?

  5. A town's population is y = 7500(1.06)^t after t years. Ari wonders: by what percent does it grow each year?

  6. A used scooter's value is y = 240(0.97)^t after t months. Bo asks: by what percent does it drop each month?

  7. Jun's town has 6,000 people and shrinks 4% each year. Which equation gives the amount y after t years?

    • y = 6000(1.04)^t
    • y = 6000(0.96)^t
    • y = 6000(0.04)^t
    • y = 6000 − 240t
  8. A fern patch in Kira's garden bed covers 20 square cm and grows 15% each week. Which equation gives the amount y after t weeks?

    • y = 20(1.15)^t
    • y = 20 + 3t
    • y = 20(0.15)^t
  9. Luz shines 900 lux through layers of film, and each layer blocks 25% of the light reaching it. Which equation gives the amount y after t layers?

    • y = 900(0.75)^t
    • y = 900(1.25)^t
    • y = 900(0.25)^t
  10. Milo's bike club has 50 members and grows 8% each month. Which equation gives the amount y after t months?

    • y = 50(0.08)^t
    • y = 50(1.08)^t
    • y = 50 + 4t
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Exponential growth and decay

Answer Key - Grade 9 Math Worksheet

Circle the best answer, or write your answer on the line.

  1. Esme's school robotics club grows by 12% each year. What number goes on each arrow of the growth table?

    1.12
  2. Each wash fades the dye in Jun's shirt by 6%. What number goes on each arrow of the growth table?

    0.94
  3. Noah looks up a used bike worth $360. Its value drops 15% each year. To the nearest dollar, what is it worth after 4 years?

    $188
  4. Zee's notes say the light through t layers of film is y = 1200(0.85)^t. By what percent does the light drop with each layer?

    15
  5. A town's population is y = 7500(1.06)^t after t years. Ari wonders: by what percent does it grow each year?

    6
  6. A used scooter's value is y = 240(0.97)^t after t months. Bo asks: by what percent does it drop each month?

    3
  7. Jun's town has 6,000 people and shrinks 4% each year. Which equation gives the amount y after t years?

    • y = 6000(1.04)^t
    • y = 6000(0.96)^t
    • y = 6000(0.04)^t
    • y = 6000 − 240t
  8. A fern patch in Kira's garden bed covers 20 square cm and grows 15% each week. Which equation gives the amount y after t weeks?

    • y = 20(1.15)^t
    • y = 20 + 3t
    • y = 20(0.15)^t
  9. Luz shines 900 lux through layers of film, and each layer blocks 25% of the light reaching it. Which equation gives the amount y after t layers?

    • y = 900(0.75)^t
    • y = 900(1.25)^t
    • y = 900(0.25)^t
  10. Milo's bike club has 50 members and grows 8% each month. Which equation gives the amount y after t months?

    • y = 50(0.08)^t
    • y = 50(1.08)^t
    • y = 50 + 4t