Radius of the earth is `6.40 xx 10^6` m. Find the diameter of the earth.

Answer

To find the diameter of the Earth given its radius, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Given Data**:
The radius of the Earth (r) is given as \( 6.40 \times 10^6 \) meters.

2. **Understand the Relationship**:
The relationship between the diameter (d) and the radius (r) is given by the formula:
\[ d = 2 \times r \]

3. **Substitute the Value of the Radius**:
Now, substitute the value of the radius into the formula:
\[ d = 2 \times (6.40 \times 10^6 \text{ m}) \]

4. **Perform the Calculation**:
Calculate the diameter:
\[ d = 2 \times 6.40 \times 10^6 = 12.80 \times 10^6 \text{ m} \]

5. **Express in Standard Scientific Notation**:
The diameter can also be expressed in scientific notation:
\[ d = 1.28 \times 10^7 \text{ m} \]

### Final Answer:
The diameter of the Earth is \( 1.28 \times 10^7 \) meters.

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