Question 168932
Given that weogh vaores with square of distance from center. Given 250 pounds at 3960 miles.

{{{W = C/(D^2)}}} where W is weight, D is distance to center of earth in miles and C is some constant.  

Let X be the weight in the airplane and Y be the distance from the center of the earth to the airplane.

{{{Y = 3960 + 30000/5280}}} Need to convert 30000 feet into miles. 5280feet in a mile.
{{{Y = 3965.68}}} miles

{{{W*D^2 = C}}}
So
{{{250*3960^2 = X * 3965.68^2}}}
{{{(250*3960^2)/(3965.68^2) = X}}}

You can crunch the numbers from here