We're told oxygen is the most common element in the Earth's solid crust. But how much oxygen is there? Let's compare to the amount of oxygen in the Earth's atmosphere, like this: The most common minerals in the Earth's crust are feldspars, and sanidine KAlSi3O8 is a typical feldspar. Let's assume the entire crust is made of sanidine, with a density of /2.5gcm3.

The radius of the Earth is 6371.km and let's say the crust is the upper 75.0 km of it.

Let's model the Earth's atmosphere as a layer on top of the Earth about 100.km thick with an average density of /0.99gm3, and which is 23.1% oxygen by mass.

Use this information to calculate the ratio of the mass of oxygen in the Earth's atmosphere to the mass of oxygen in the Earth's crust. Round your answer to 2 significant digits.