Mathematics Grade 7 15 min

Inequalities with decimals

Inequalities with decimals

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Introduction & Learning Objectives

Learning Objectives Identify and correctly use inequality symbols (<, >, ≤, ≥). Compare any two decimal numbers using appropriate inequality symbols. Order a set of three or more decimal numbers from least to greatest or greatest to least. Solve one-step linear inequalities involving addition or subtraction of decimals. Represent the solution set of a decimal inequality on a number line. Apply inequalities with decimals to solve simple real-world problems. Have you ever needed to compare prices at a store to find the best deal, or check if a measurement is within a certain limit? 🤔 This often involves comparing numbers with decimals! In this lesson, you will learn how to compare and order decimal numbers using special symbols called inequalities. You'll also dis...
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Key Concepts & Vocabulary

TermDefinitionExample InequalityA mathematical statement that compares two expressions using an inequality symbol, showing that one is not necessarily equal to the other.3.5 < 4.2 (3.5 is less than 4.2) DecimalA number that includes a decimal point, representing a fractional part of a whole number. It uses place values like tenths, hundredths, and thousandths.0.75 (seventy-five hundredths), 12.3 (twelve and three tenths) Greater Than (>)An inequality symbol used to show that the number on the left side is larger than the number on the right side.5.8 > 5.1 (5.8 is greater than 5.1) Less Than (<)An inequality symbol used to show that the number on the left side is smaller than the number on the right side.0.25 < 0.3 (0.25 is less than 0.3) Greater Than or Equal To (≥)An inequ...
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Core Formulas

Rule for Comparing Decimals To compare two decimals, align their decimal points and compare the digits from left to right, starting with the largest place value. If necessary, add trailing zeros to the end of the decimal with fewer digits to make them have the same number of decimal places. This rule helps you accurately determine which decimal is larger or smaller by ensuring you compare digits of the same place value. Addition/Subtraction Property of Inequality If $a < b$, then $a + c < b + c$ and $a - c < b - c$. This also applies to >, ≤, and ≥. You can add or subtract the same decimal number from both sides of an inequality without changing the direction of the inequality symbol. This is useful for isolating a variable. Multiplication/Division Property o...

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Sample Practice Questions

Challenging
An elevator has a weight limit of 450.5 kilograms. There are already two boxes in the elevator weighing 80.25 kg and 115.8 kg. Which inequality could be used to find 'w', the maximum additional weight the elevator can hold?
A.w + 80.25 + 115.8 > 450.5
B.w - (80.25 + 115.8) ≤ 450.5
C.w + 80.25 + 115.8 ≤ 450.5
D.450.5 - w ≤ 80.25 + 115.8
Challenging
A student was asked to graph the solution for p + 3.2 ≥ 1.7. They drew a number line with a closed circle on -1.5 and shaded to the left. What is the error in their graph?
A.The circle should be open, not closed.
B.The shading should be to the right, not the left.
C.The circle is on the wrong number; it should be on 4.9.
D.There are two errors: the circle should be open and shaded to the right.
Challenging
Which of the following decimal values for 'x' makes the compound inequality 1.05 < x ≤ 1.5 true?
A.1.05
B.1.55
C.1.049
D.1.45

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