<PRE><B>Question 1083705</B>
The solution is to sum a geometric series
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The tennis ball is dropped from a height of 20 m.  After it hits the floor, it reaches a height of 20 * 0.40 = 8 m
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After it hits the floor for the second time, it reaches a height of 8 * 0.40 = 3.2 m
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and so forth
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Note that after bouncing to a distance, it falls that same distance
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let d(n) be the distance the tennis ball has traveled when it hits the floor for the nth time, then
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d(1) = 20
d(2) = 20 + 2 * 20 * 0.40
d(3) = 20 + 2 * 20 * 0.40 + 2 * 20 *(0.40)^2
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therefore,
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d(n) = 20 + 2 * 20 * 0.40 + .... + 2 * 20 * (0.40)^(n-1)
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d(6) = 20 * ( 1 - 0.40^6) / ( 1 - 0.40) =  33.2 m
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the tennis ball travels 33.2 m after it hits the floor for the 6th time
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