Questions on Algebra: Expressions involving variables, substitution answered by real tutors!

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Question 168931: The weight of an object varies inversely with the square of the distance from earth's center (3,960 miles). A man weighs 250 lbs on the surface of the earth. How much would he weigh in an airplane flying at 30,000 ft?: The weight of an object varies inversely with the square of the distance from earth's center (3,960 miles). A man weighs 250 lbs on the surface of the earth. How much would he weigh in an airplane flying at 30,000 ft?
Answer by Alan3354(1926) About Me  (Show Source):
You can put this solution on YOUR website!
The weight of an object varies inversely with the square of the distance from earth's center (3,960 miles). A man weighs 250 lbs on the surface of the earth. How much would he weigh in an airplane flying at 30,000 ft?
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3960 miles = 3960*5280 feet = 20908800 feet
His weight at 30000 feet above that is
250*((20908800)/(20908800+30000))^2
= 250*(209088/209388)^2
= 249.284 pounds
That's a difference of 0.716 pounds, or 11.45 ounces.