Lindbergh's Air Speed Charles Lindbergh estimated that at the start of his historic flight the practical economical air speed wa
s 95 mph and at 4000 statute miles from the starting point it was 75 mph (www.charleslindbergh.com). Assume that the practical cconomical air speed S is a linear function of the distance D from the starting point as shown in the accompanying figure. Find a formula for that function.
