Year 7 CIE Maths: Unit Test Mock Paper Walkthrough | Year 7 CIE 数学：单元测试模拟卷解析

📚 Year 7 CIE Maths: Unit Test Mock Paper Walkthrough | Year 7 CIE 数学：单元测试模拟卷解析

Welcome to the walkthrough of our Year 7 CIE Mathematics unit test mock paper. This resource will guide you through every question, explaining the key steps, common pitfalls and best strategies. By studying these detailed solutions, you will reinforce your understanding of numbers, algebra, geometry and data handling at the Stage 7 level.

欢迎阅读 Year 7 CIE 数学单元测试模拟卷的逐题解析。本资源将带你回顾每一道题目，讲解关键步骤、常见错误和最佳解题策略。通过学习这些详细解答，你将巩固对数字、代数、几何和数据处理这些 Stage 7 级别内容的理解。

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1. Question 1 – Order of Operations | 第1题 – 运算顺序

Question: Evaluate 36 – 24 ÷ (3 + 1) × 2 + 5².

题目：计算 36 – 24 ÷ (3 + 1) × 2 + 5².

This question tests your understanding of BODMAS (Brackets, Orders, Division/Multiplication, Addition/Subtraction). Always solve calculations in the correct sequence.

这道题考察你对 BODMAS（括号、指数、乘除、加减）规则的理解。务必按照正确的顺序计算。

Step 1: Work inside the brackets first: (3 + 1) = 4.

步骤1：先计算括号里的内容：(3 + 1) = 4。

Step 2: Evaluate the exponent (order): 5² = 5 × 5 = 25.

步骤2：计算指数（乘方）：5² = 5 × 5 = 25。

Step 3: Now perform division and multiplication from left to right. The expression becomes 36 – 24 ÷ 4 × 2 + 25. Divide first: 24 ÷ 4 = 6, then multiply: 6 × 2 = 12.

步骤3：现在从左到右进行乘除运算。表达式变为 36 – 24 ÷ 4 × 2 + 25。先除：24 ÷ 4 = 6，再乘：6 × 2 = 12。

Step 4: Substitute back to get 36 – 12 + 25.

步骤4：代回后得到 36 – 12 + 25。

Step 5: Complete addition and subtraction from left to right: 36 – 12 = 24, then 24 + 25 = 49.

步骤5：从左到右完成加减运算：36 – 12 = 24，然后 24 + 25 = 49。

Answer: 49

答案：49

Important: A common error is to subtract 12 + 25 first and get -1. Always stick to left-to-right order for addition and subtraction.

重要提醒：常见错误是先计算 12 + 25，再减去得到 -1。加减运算一定要严格从左到右进行。

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2. Question 2 – Adding Fractions | 第2题 – 分数加法

Question: Work out 2 1/3 + 3/4.

题目：计算 2 1/3 + 3/4。

Adding mixed numbers and fractions requires switching to improper fractions and finding a common denominator.

带分数和真分数相加，需要先转化为假分数，再找到公分母。

Step 1: Convert the mixed number 2 1/3 to an improper fraction: (2 × 3 + 1)/3 = 7/3.

步骤1：将带分数 2 1/3 化为假分数：(2 × 3 + 1)/3 = 7/3。

Step 2: Write the problem as 7/3 + 3/4. The denominators are 3 and 4. The lowest common multiple is 12.

步骤2：题目转换为 7/3 + 3/4。分母分别是 3 和 4，最小公倍数为 12。

Step 3: Multiply numerator and denominator of 7/3 by 4 to get 28/12. Multiply 3/4 by 3 to get 9/12.

步骤3：将 7/3 的分子分母同乘 4，得到 28/12；将 3/4 的分子分母同乘 3，得到 9/12。

Step 4: Now add the numerators over the common denominator: 28/12 + 9/12 = 37/12.

步骤4：现在分母不变，分子相加：28/12 + 9/12 = 37/12。

Step 5: Convert 37/12 back to a mixed number: 12 goes into 37 three times (3 × 12 = 36), with remainder 1, so 3 1/12.

步骤5：将 37/12 化回带分数：12 乘以 3 得 36，余 1，所以是 3 1/12。

Answer: 3 1/12

答案：3 1/12

Always simplify if possible. Here 1/12 is already in simplest form.

记得如果可能要进行约分。这里 1/12 已经是最简分数。

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3. Question 3 – Multiplying Decimals | 第3题 – 小数乘法

Question: Calculate 0.6 × 0.8.

题目：计算 0.6 × 0.8。

Multiplying decimals can be made easier by thinking of them as fractions or by counting decimal places.

小数乘法可以通过转化为分数或数位小数位数来简化。

Method 1 – Fractions: 0.6 = 6/10, 0.8 = 8/10. Multiply: (6 × 8) / (10 × 10) = 48/100 = 0.48.

方法1 – 分数：0.6 = 6/10，0.8 = 8/10。相乘：(6 × 8) / (10 × 10) = 48/100 = 0.48。

Method 2 – Decimal place counting: Ignore decimals, multiply 6 × 8 = 48. Each number has 1 decimal place, so total 2 decimal places in the answer → 0.48.

方法2 – 数小数位数：忽略小数点，计算 6 × 8 = 48。每个数有 1 位小数，所以答案共 2 位小数 → 0.48。

Answer: 0.48

答案：0.48

Be careful not to miss the decimal point. A typical mistake is writing 4.8 instead of 0.48.

小心不要漏掉小数点。常见错误是将答案写成 4.8 而不是 0.48。

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4. Question 4 – Percentage of an Amount | 第4题 – 求一个数的百分之几

Question: Find 15% of 200.

题目：求 200 的 15%。

Finding a percentage of a quantity means multiplying by the percentage as a fraction or decimal.

求一个数量的百分之几，就是将这个数量乘以百分数对应的分数或小数。

Step 1: Write 15% as a fraction: 15/100. Then multiply by 200: (15/100) × 200.

步骤1：将 15% 写成分数：15/100。然后乘以 200：(15/100) × 200。

Step 2: Simplify: (15 × 200) / 100 = 3000 / 100 = 30.

步骤2：化简：(15 × 200) / 100

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