Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Understanding Fractions: A fraction is a part of a whole, written in the form , where is the numerator (parts taken) and is the denominator (total parts). Visually, if you divide a rectangular chocolate bar into equal pieces and eat , the fraction eaten is .
Like Fractions: These are fractions that have the same denominator, such as and . When denominators are the same, the fraction with the larger numerator is the greater fraction. Visually, if two identical circles are both divided into equal slices, slices will cover a larger area than slices.
Unlike Fractions with Same Numerator: If two fractions have the same numerator but different denominators (e.g., and ), the fraction with the smaller denominator is larger. Visually, if you cut a pizza into large slices, one slice is bigger than if you cut the same pizza into smaller slices.
Unlike Fractions with Different Denominators: To compare fractions where both parts are different (e.g., and ), we must first make them 'like' fractions by finding a common denominator, usually the Least Common Multiple (LCM) of the denominators.
Equivalent Fractions: These are fractions that represent the same value, even if they look different. For example, , , and are all equivalent. Visually, shading half of a circle looks the same regardless of whether it is divided into large parts or small parts.
The Cross-Multiplication Rule: A quick way to compare any two fractions and is to cross-multiply. We compare the products and . If is greater, then is the larger fraction.
Ordering Fractions: Fractions can be arranged in Ascending Order (smallest to largest) or Descending Order (largest to smallest) by converting all given unlike fractions into like fractions using their LCM and then comparing their numerators.
📐Formulae
Like Fractions Comparison: If , then if
Same Numerator Comparison: If , then if
Cross-Multiplication Method: For and , calculate and . If , then
Equivalent Fraction: (where )
💡Examples
Problem 1:
Compare the fractions and to find which one is greater.
Solution:
Step 1: Find the LCM of the denominators and . Since they are co-prime, . \ Step 2: Convert both fractions to equivalent fractions with denominator . \ \ \ Step 3: Compare the numerators of the like fractions. \ Since , it follows that . \ Therefore, .
Explanation:
This solution uses the common denominator method. By making the parts the same size (35ths), we can directly compare how many parts each fraction has.
Problem 2:
Arrange the following fractions in ascending order: .
Solution:
Step 1: Find the LCM of and . \ Multiples of \ Multiples of \ Multiples of \ So, . \ Step 2: Convert to like fractions with denominator . \ \ \ \ Step 3: Compare numerators: . \ Thus, . \ Final Answer: .
Explanation:
To order multiple unlike fractions, we convert them all to a common denominator and then arrange them based on their numerators from smallest to largest.