To find the area of a circle, we use the formula:
\[ \text{Area} = \pi r^2 \]
where \( r \) is the radius of the circle.
- Find the radius: The radius is half of the diameter. Given that the diameter of the circle is 10 millimeters, we calculate the radius as follows:
\[ r = \frac{\text{diameter}}{2} = \frac{10 \text{ mm}}{2} = 5 \text{ mm} \]
- Substitute the radius into the area formula: Now that we have the radius, we can substitute it into the area formula:
\[ \text{Area} = \pi (5 \text{ mm})^2 \]
- Calculate \( 5^2 \):
\[ 5^2 = 25 \]
- Use \(\pi \approx 3.14\): Now substitute the value of \(\pi\):
\[ \text{Area} \approx 3.14 \times 25 \]
- Calculate the area: Multiply \( 3.14 \) by \( 25 \):
\[ 3.14 \times 25 = 78.5 \text{ square mm} \]
Thus, the estimated area of the circle to the tenths place is:
\[ \text{Area} \approx 78.5 \text{ square mm} \]
Therefore, the correct response is:
78.5 square mm.