Please help me The diameter of a planet is about 26,590 mi. The diameter of the planet's moon is about 28% of the diameter of the planet. What percent of the volume of the planet is the volume of its moon?

2.195%

Step-by-step explanation:

Assuming that both planets are a sphere, we have to:

26590 * 28% = 7445.2

7445.2 miles would be the diameter of the moon, now to calculate the volume, we know that the radius is half the diameter, so:

r2 = d2 / 2 = 7445.2 / 2 = 3722.6

and the radius of the planet would be:

r1 = d1 / 2 = 26590/2 = 13295

now the volume of the planet we know is equal to:

v1 = 4/3 * pi * r1 ^ 3

and the volume of the moon would be:

v2 = 4/3 * pi * r2 ^ 3

We want to calculate the percentage by volume, therefore:

v2 / v1 = 4/3 * pi * r2 ^ 3 / 4/3 * pi * r1 ^ 3

v2 / v1 = 3722.6 ^ 3/13295 ^ 3

v2 / v1 = 0.021952

that is, the volume of the moon represents 2.195%