Grade: 4 Subject: Math Unit: Decimals Introduction Lesson: 4 of 6 SAT: ProblemSolving+DataAnalysis ACT: Math

Word Problems

Learn

In this lesson, you will apply your decimal knowledge to real-world word problems. Decimals appear in many everyday situations, especially with money and measurements.

Where Do We See Decimals?

  • Money: Prices like $4.99 or $12.50
  • Measurements: Height (5.5 feet), weight (3.25 pounds)
  • Sports: Race times (9.58 seconds), batting averages (0.325)
  • Science: Temperature readings, precise measurements

Problem-Solving Steps

  1. Read the problem carefully
  2. Identify the decimals and what they represent
  3. Decide what operation is needed
  4. Solve and check your answer

Examples

Work through these examples to see the concepts in action.

Example 1: Money Comparison

Sarah has $5.75 and Jake has $5.80. Who has more money?

Solution: Compare 5.75 and 5.80. Since 80 hundredths > 75 hundredths, Jake has more money.

Example 2: Measurement

A pencil is 0.19 meters long. Another pencil is 0.2 meters long. Which is longer?

Solution: Rewrite 0.2 as 0.20. Compare: 0.20 > 0.19. The second pencil is longer.

✏️ Practice

Test your understanding with these practice questions.

Practice Questions

0/4 correct
Question 1

If y = 3x represents a proportional relationship, what is the constant of proportionality?

A 1
B 3
C x
D y
Explanation: In y = kx, the constant of proportionality k is the coefficient of x. Here k = 3.
Question 2

A recipe uses 2 cups of flour for every 3 cups of sugar. If you use 6 cups of flour, how many cups of sugar do you need?

A 4 cups
B 9 cups
C 12 cups
D 8 cups
Explanation: Set up the proportion: 2/3 = 6/x. Cross multiply: 2x = 18, so x = 9 cups.
Question 3

Which equation represents a proportional relationship?

A y = 2x + 1
B y = 5x
C y = x²
D y = 3
Explanation: A proportional relationship has the form y = kx where k is a constant. Only y = 5x fits this form.
Question 4

The table shows x: 2, 4, 6 and y: 8, 16, 24. What is the constant of proportionality?

A 2
B 4
C 6
D 8
Explanation: Divide any y-value by its corresponding x-value: 8÷2 = 4, 16÷4 = 4, 24÷6 = 4. The constant is 4.

Check Your Understanding

Test yourself with these 10 review questions. Click each question to reveal the answer.

Question 1: A book costs $8.99 and a notebook costs $3.50. Which item costs more?

Answer: The book costs more. $8.99 > $3.50 because 8 > 3 in the ones place.

Question 2: Maria ran 2.4 miles and Tom ran 2.35 miles. Who ran farther?

Answer: Maria ran farther. Rewrite 2.4 as 2.40. Then 2.40 > 2.35.

Question 3: A candy bar weighs 0.15 kg. A bag of chips weighs 0.2 kg. Which weighs more?

Answer: The bag of chips weighs more. Rewrite 0.2 as 0.20. Then 0.20 > 0.15.

Question 4: Three friends measured their heights: Alex is 1.32 m, Ben is 1.3 m, and Cara is 1.29 m. Order them from shortest to tallest.

Answer: Cara (1.29 m), Ben (1.30 m), Alex (1.32 m). Convert 1.3 to 1.30 to compare.

Question 5: A store sells apples for $0.75 each and oranges for $0.8 each. Which fruit costs more per piece?

Answer: Oranges cost more. Rewrite $0.8 as $0.80. Then $0.80 > $0.75.

Question 6: Sam scored 9.5 points and Kim scored 9.45 points in a gymnastics competition. Who scored higher?

Answer: Sam scored higher. Rewrite 9.5 as 9.50. Then 9.50 > 9.45.

Question 7: A recipe calls for 0.25 cups of sugar. Another recipe needs 0.3 cups. Which recipe uses more sugar?

Answer: The second recipe uses more sugar. Rewrite 0.3 as 0.30. Then 0.30 > 0.25.

Question 8: Three race times were recorded: 12.5 seconds, 12.48 seconds, and 12.55 seconds. Order from fastest to slowest.

Answer: 12.48 s (fastest), 12.50 s (12.5), 12.55 s (slowest). Lower times are faster.

Question 9: A container holds 1.5 liters. Another holds 1.45 liters. Which holds more?

Answer: The first container holds more. Rewrite 1.5 as 1.50. Then 1.50 > 1.45.

Question 10: Emma has $10.09 and Liam has $10.9. Who has more money?

Answer: Liam has more money. Rewrite $10.9 as $10.90. Then $10.90 > $10.09.

Next Steps

  • Review any concepts that felt challenging
  • Move on to the next lesson when ready
  • Return to practice problems periodically for review