Question

How many pieces of 25 cm length can be cut from a rod 42.5 meter long?

• A. 170
• B. 180
• C. 165
• D. 150

Hint:

To divide by 25 easily:
Remember that $25 = \frac{100}{4}$.
Therefore, dividing a number by 25 is the same as multiplying it by 4 and dividing by 100:
\[ \frac{4250}{25} = \frac{4250 \times 4}{100} = \frac{17000}{100} = 170. \]
This mental math trick saves time during exams.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
To solve division problems involving physical measurements, we must first convert all measurements into the same unit.
Once the units are uniform, the total number of pieces is found by dividing the total length of the rod by the length of each individual piece.
Key Formula or Approach:
The conversion rate between meters and centimeters is: \[ 1\text{ meter} = 100\text{ cm} \] The formula to find the number of pieces is: \[ \text{Number of pieces} = \frac{\text{Total Length of Rod}}{\text{Length of each piece}} \]

Step 2: Detailed Explanation:
Let us perform the calculations step-by-step:
1. Convert the total length of the rod to centimeters:
- Total length of rod $= 42.5\text{ meters}$
\[ \text{Total Length} = 42.5 \times 100\text{ cm} = 4250\text{ cm} \] 2. Calculate the number of pieces:
- Length of each piece $= 25\text{ cm}$
\[ \text{Number of pieces} = \frac{4250\text{ cm}}{25\text{ cm}} \] - Perform the division: \[ \text{Number of pieces} = 170 \] Therefore, $170$ pieces of $25\text{ cm}$ length can be cut from the rod.

Step 3: Final Answer:
The number of pieces that can be cut is 170.
Therefore, the correct option is (A).