Practice Maths

Percentage Increase and Decrease — Solutions

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  1. Percentage increases

    1. Increase 200 by 10%:
    2. Increase $80 by 25%:
    3. Increase 150 kg by 20%:
    4. Increase $360 by 15%:
    5. Increase 500 m by 8%:
    6. Increase 75 by 40%:
    7. Increase $1200 by 5%:
    8. Increase 640 by 12.5%:

  2. Percentage decreases

    1. Decrease 300 by 10%:
    2. Decrease $240 by 25%:
    3. Decrease 180 km by 30%:
    4. Decrease $450 by 20%:
    5. Decrease 800 mL by 5%:
    6. Decrease 96 by 12.5%:
    7. Decrease $2500 by 8%:
    8. Decrease 160 by 35%:

  3. Finding the % change

    1. 50 → 65:
    2. 120 → 90:
    3. $40 → $46:
    4. 80 kg → 68 kg:
    5. $350 → $385:
    6. 250 → 175:

  4. Working backwards

    1. After 20% increase = $120:
    2. After 10% decrease = 72:
    3. After 25% increase = 250:
    4. After 15% decrease = $2550:

  5. Problem solving

    1. Mark-up of 35% on $480:
    2. Car $28 000 decreases 18%:
    3. Population 15 000 grows 12%:
    4. Score 56 → 70:
    5. Jacket $240, −30%, then −20%:

  6. More increase and decrease calculations

    1. Increase $4500 by 6%:
    2. Decrease 960 by 37.5%:
    3. Increase 72 kg by 16⅔%:
    4. Decrease $3200 by 12.5%:
    5. Increase 0.8 km by 25%:
    6. Decrease 144 by 33⅓%:

  7. Multiplier identification

    1. Increase by 7%:
    2. Decrease by 4%:
    3. Increase by 100%:
    4. Decrease by 100%:
    5. Increase by 0.5%:
    6. Decrease by 33⅓%:
    7. Decrease by 2.5%:
    8. Increase by 250%:

  8. Percentage change calculations

    1. 400 → 460:
    2. $75 → $60:
    3. 1200 → 900:
    4. $0.80 → $1.00:
    5. 48 kg → 52 kg:
    6. 360 → 270:

  9. Finding the original value

    1. After 30% increase = 390:
    2. After 40% decrease = 54:
    3. Price inc. GST = $242:
    4. 8% growth to 16 200:
    5. After 5% rise = $630:

  10. Extended percentage change problems

    1. House value 2022–2024:
    2. School enrolment 672 after 12% growth:
    3. Run time 48 min → 42 min:
    4. +20% then −20%:
    5. Revenue over 3 years from $200 000: