Lesson 1.15: Decimals – Word Problems & Introduction to Percent | SEA Mathematics | My Carib Academy
SEA 2025-2028 Framework Aligned

💰 Lesson 1.15: Decimals – Word Problems & Introduction to Percent

Master decimal word problems (money, best buy, profit/loss) and introduction to percent (10%, 25%, 50%, conversions). This lesson covers SEA Mathematics Objectives 88-92 from the Number Strand.

70 Minutes
Module 1: Number
Objectives 88-92
3 Videos
Lesson Progress 0%

Previous Lesson

Did you complete Lesson 1.14? Review Decimal Operations →

Learning Objectives

By the end of this lesson, you will be able to:

  • Solve decimal word problems involving money (Objective 88)
  • Compare prices to find the best buy (Objective 88)
  • Calculate profit and loss (Objective 88)
  • Understand percent as parts per hundred (Objectives 89-90)
  • Find 10%, 25%, and 50% of amounts (Objectives 91-92)
  • Convert between fractions, decimals and percents (Objectives 89-92)

SEA Tip

Decimal word problems and percent questions appear in Section II and III of the SEA Math paper. These are practical life skills! (SEA Framework Page 21-22)

Watch: Best Buy Problems

Start by watching this video to learn how to compare prices and find the best buy. Take notes as you watch! 📝

Best Buy Problems – Mathematics Video Lesson

Quick Check

Did you understand the video? Review the notes below before continuing! ✅

Decimal Word Problems: Money & Best Buy

Decimal word problems help you make smart money decisions in real life!

📋 Best Buy Strategy:

How to Find the Best Buy
  1. Find the unit price (price per item)
  2. Divide total price by number of items
  3. Compare unit prices
  4. Choose the lower unit price

📊 Example 1: Best Buy Problem

Which is the Better Buy?

Option A: 6 pens for $12.00

Option B: 10 pens for $18.00

Solution:

  1. Option A: $12.00 ÷ 6 = $2.00 per pen
  2. Option B: $18.00 ÷ 10 = $1.80 per pen
  3. Compare: $1.80 < $2.00

Answer: Option B is the better buy (saves $0.20 per pen)

Watch: Profit and Loss

Now watch this video to learn how to calculate profit and loss. Pay attention to the formulas! 🎯

Profit and Loss – Mathematics Video Lesson

Profit and Loss

Understanding profit and loss helps you understand business and money management!

📋 Profit and Loss Formulas:

Key Formulas
Concept Formula
Profit Selling Price − Cost Price
Loss Cost Price − Selling Price
Selling Price (Profit) Cost Price + Profit
Selling Price (Loss) Cost Price − Loss

📊 Example 2: Profit Problem

Calculating Profit

Question: Maria bought a dress for $80.00 and sold it for $120.00. What was her profit?

Solution:

  1. Cost Price: $80.00
  2. Selling Price: $120.00
  3. Profit: $120.00 − $80.00 = $40.00

Answer: $40.00 profit

📊 Example 3: Loss Problem

Calculating Loss

Question: John bought a phone for $500.00 and sold it for $450.00. What was his loss?

Solution:

  1. Cost Price: $500.00
  2. Selling Price: $450.00
  3. Loss: $500.00 − $450.00 = $50.00

Answer: $50.00 loss

Watch: Introduction to Percent

Watch this video to learn about percent and how to find 10%, 25%, and 50% of amounts. 🎯

Introduction to Percent – Mathematics Video Lesson

Introduction to Percent

Percent means “per hundred” or “out of 100”. The symbol for percent is %.

Understanding Percent

  • 10% = 10/100 = 0.10 = 1/10 (divide by 10)
  • 25% = 25/100 = 0.25 = 1/4 (divide by 4)
  • 50% = 50/100 = 0.50 = 1/2 (divide by 2)
  • 100% = 100/100 = 1.00 = 1 (the whole amount)

📋 Finding Common Percents:

Quick Methods
Percent Fraction Method Example
10% 1/10 Divide by 10 10% of 80 = 80 ÷ 10 = 8
25% 1/4 Divide by 4 25% of 80 = 80 ÷ 4 = 20
50% 1/2 Divide by 2 50% of 80 = 80 ÷ 2 = 40

📊 Example 4: Finding 10%

10% of $60.00

Solution:

  1. 10% = 1/10
  2. Divide by 10: $60.00 ÷ 10 = $6.00

Answer: $6.00

📊 Example 5: Finding 25%

25% of $80.00

Solution:

  1. 25% = 1/4
  2. Divide by 4: $80.00 ÷ 4 = $20.00

Answer: $20.00

📊 Example 6: Finding 50%

50% of $150.00

Solution:

  1. 50% = 1/2
  2. Divide by 2: $150.00 ÷ 2 = $75.00

Answer: $75.00

Memory Trick

10% = Move decimal one place left
25% = Divide by 4 (quarter)
50% = Divide by 2 (half)

Quick Quiz

Test your understanding! Select an answer for each question. 💰

6 Questions
12 Minutes
70% to Pass

1. Option A: 5 pencils for $10. Option B: 8 pencils for $12. Which is the better buy?

2. Cost Price: $50, Selling Price: $70. What is the profit?

3. Cost Price: $100, Selling Price: $80. What is the loss?

4. What is 10% of $90?

5. What is 25% of $100?

6. What is 50% of $200?

0/6

Lesson Complete!

Great job finishing Lesson 1.15! You’re mastering decimal word problems and percent for the SEA exam! 🎉

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