<PRE><B>Question 207642</B>
T[0] = temperature at ground level = 70 degrees.
formula is T[0] - (5.5/1000)*h
I am presuming h is in feet since the answer you gave is 6909 feet.
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1 mile is 5280 feet.
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temperature 1 miles up should be 70 - (5.5/1000)*5280 = 40.96 degrees.
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since freezing is 32 degrees (fahrenheit
70 - (5.5/1000)*h = 32
solving for h we:
subtract 32 from both sides of the equation to get:
70 - 32 = 5.5/1000*h 
simplifying we get:
38 = 5.5/1000*h
we multiply both sides of the equation by 1000/5.5 to get:
38*1000/5.5 = h
we simplify to get:
h = 38*1000/5.5 = 6909.090909 = 6909 rounded to the nearest integer.
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looks like 6909 was the right number.
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