Percentage Change Calculations

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📊 Part 1: Basic Percentage Change

WALT: Calculate the percentage increase or decrease between two numbers

1. A jacket costs $80 at the start of winter. By the end of winter, it costs $60. What is the percentage decrease?

2. The price of petrol increased from $2.20 per litre to $2.53 per litre. What is the percentage increase?

3. A local café had 150 customers in January. In February, they had 180 customers. Calculate the percentage increase.

4. Choose the correct formula for percentage change:

(New Value - Old Value) ÷ Old Value × 100%

(Old Value - New Value) ÷ New Value × 100%

(New Value ÷ Old Value) × 100%

🔢 Part 2: Decimal Multipliers

Remember: For increases, multiply by (1 + percentage as decimal). For decreases, multiply by (1 - percentage as decimal).

5. Complete the decimal multipliers:

a) 15% increase: multiply by ________

b) 25% decrease: multiply by ________

c) 8% increase: multiply by ________

d) 30% decrease: multiply by ________

6. A rugby jersey costs $120. During a sale, it has a 20% discount. Using a decimal multiplier, find the sale price.

7. A savings account has $500. After earning 3% interest, what is the new balance? Use the multiplier method.

🏪 Part 3: Real-World Applications

8. A local marae is fundraising for new kitchen equipment. They raised $2,400 in March and $3,000 in April. What was the percentage increase in fundraising?

9. Boxing Day Sale Problem: A television originally costs $1,200. It's marked down 35% for Boxing Day, then has an additional 10% taken off the sale price for cash payment. What is the final price?

10. Which situations involve percentage increases? (Tick all that apply)

GST added to purchases

Student discount on movie tickets

Interest earned on savings

Mark-up on retail prices

Sale discounts

11. Reflection: Describe one situation from your own life where understanding percentage change would be helpful.