The diameter of a penny is about 1.9 space x space 10 to the power of negative 5 end exponent km. It would take about 2.1 space x space 10 to the power of 9 pennies placed side by side to circle the equator once. What is the approximate length of the equator? Show work using scientific notation. Write final answer in standard form.

1.0 * 10^4 km

Step-by-step explanation:

This is quite straightforward. We only need to multiply the diameter of each penny in km by the number of pennies.

This equal to:

1.5 * 10^-5 * 2.1 * 10^9 = 3.15 * 10^4 km.

Now this is the circumference of the circle formed around the equator. To get the length of the equator,

we simply calculate the diameter of this circle.

The diameter is related to the circumference through the formula

Circumference of circle = π x Diameter of circle

We only need to divide the circumference by pi

This equals:

3.15 * 10^4 * 7/22 = 1.0 * 10^4