Mastering Percentages: Decimal Multipliers and Real-World Applications
This guide teaches you how to calculate percentages using decimal multipliers effectively. Learn how to find a percentage of an amount, apply increases and decreases to various values, and determine original prices after discounts. Through practical examples, such as calculating percentages of salaries and prices, you will master the skills necessary to navigate percentage problems confidently. Complete the exercises provided to reinforce your learning and gain proficiency in percentage calculations.
Mastering Percentages: Decimal Multipliers and Real-World Applications
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Presentation Transcript
Percentages Level 8
Using the Decimal Multiplier to Find Percentages. • Example: Find 12% of £54? Decimal = 12% = 12 = 12 ÷ 100 = 0.12 multiplier 100 On calculator: = 6.48 = £6.48 0.12 x 54
Percentage Increase • Example: Increase £24 000 by 3% • 3% of 24 000 + 100% of 24 000 • 103% of 24 000 = 103 x 24 000 100 = 1.03 x 24 000 = £24 720
Percentage Decrease • Example: Reduce £17.60 by 15% • 15% of £17.60 – answer from £17.60 • 100% of £17.60 – 15% 0f £17.60 • 85% of £17.60 (100% - 15% = 85%) = 0.85 x 17.60 = £14.96
What do you…… • Multiply a quantity by if it increased by a) 6% b) 9% c) 17.5% d) 1.25% a) 1.06 b) 1.09 c) 1.175 d) 1.0125 • Multiply a quantity by if it is decreased by a) 6% b) 9% c) 17.5% d) 1.25% a) 0.94 b) 0.91 c) 0.825 d) 0.9875
Finding the original amount • Example: John received a 20% increase in his annual salary. His new salary was £31 260. What was his salary before the rise? % increase – John’s original salary has been x 1.2 to get £31 260. x 1.2 Salary after rise £31 260 Salary before rise? ÷ 1.2 31 260 ÷ 1.2 = £26 050
Finding the original amount • Example: There was a 25% discount in a sale. A boy paid £30 for a pair of jeans in the sale. What was the original price of the jeans? % decrease - £30 has been x 0.75 to get the reduced price. x 0.75 Price after Discount £30 Price before Discount? ÷ 0.75 30 ÷ 0.75 = £40
Turn to page 188 • Complete exercise 6.1A and 6.1B • Start at question 3 • Show all your working out DON’T just write the answer. • You must complete both exercises before the end of the lesson • When you finish turn to page 189 and start exercise 6.2A. Complete all questions.
