iGCSE Mathematics (0580) -C1.9 Estimation- Exam Style Questions Paper 1- New Syllabus
▶️ Answer/Explanation
Round each number to 1 significant figure:
\(5.3 \rightarrow 5, \quad 19.5 \rightarrow 20, \quad 2.49 \rightarrow 2\)
Now calculate the estimate:
\[\frac{5 \times 20}{2} = \frac{100}{2} = 50\]
✅ Answer: \(50\)
\(5.3 \rightarrow 5, \quad 19.5 \rightarrow 20, \quad 2.49 \rightarrow 2\)
Now calculate the estimate:
\[\frac{5 \times 20}{2} = \frac{100}{2} = 50\]
✅ Answer: \(50\)
▶️ Answer/Explanation
Let’s first round every value to exactly $1$ significant figure:
• $42.8 \rightarrow 40$
• $17.4 \rightarrow 20$
• $1.97 \rightarrow 2$
• $5.79 \rightarrow 6$
Now let’s plug these simplified numbers back into our expression: $\frac{40 + 20}{2 \times 6} = \frac{60}{12}$. Simplifying this fraction gives exactly $5$.
✅ Answer: $5$
• $42.8 \rightarrow 40$
• $17.4 \rightarrow 20$
• $1.97 \rightarrow 2$
• $5.79 \rightarrow 6$
Now let’s plug these simplified numbers back into our expression: $\frac{40 + 20}{2 \times 6} = \frac{60}{12}$. Simplifying this fraction gives exactly $5$.
✅ Answer: $5$
▶️ Answer/Explanation
First, we need to round every number involved in our fraction to exactly 1 significant figure:
• $62.5$ rounds to $60$.
• $9.7$ rounds to $10$.
• $0.52$ rounds to $0.5$. Now, let’s substitute these rounded values back into the expression and solve it step-by-step: $$\text{Estimate} = \frac{60}{10 \times 0.5} = \frac{60}{5} = 12$$
Answer: 12