Question

what is the area of a circle with a diameter of 5 m? use 3.14 for pi. round to the nearest tenth. 7.9 m² 15.7 m² 19.6 m² 78.5 m²

Explanation:

Step1: Find the radius

The diameter of the circle is 5 m, and the radius \( r \) is half of the diameter. So \( r=\frac{5}{2} = 2.5 \) m.

Step2: Use the area formula for a circle

The formula for the area of a circle is \( A=\pi r^{2} \). We use \( \pi = 3.14 \) and \( r = 2.5 \) m. Substitute these values into the formula: \( A=3.14\times(2.5)^{2} \).
First, calculate \( (2.5)^{2}=6.25 \). Then, \( A = 3.14\times6.25=19.625 \) \( m^{2} \).

Step3: Round to the nearest tenth

Rounding 19.625 to the nearest tenth, we look at the hundredth place which is 2. Since 2 < 5, we keep the tenth place as it is. So 19.625 rounded to the nearest tenth is 19.6 \( m^{2} \).

Answer:

19.6 \( m^{2} \) (corresponding to the option "19.6 \( m^{2} \)")