Mark M. answered 08/31/15
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The graph of y = -0.5 l t l is an inverted "V-shaped" graph with highest point when t = 0 and y = 0.
To obtain the graph of r = -0.5 l t - 1 l + 0.5, translate the graph of y = -0.5 l t l one unit to the right and 0.5 units upward. The highest point on this graph occurs when t = 1 and r = 0.5.
Maximum rate of rainfall = 0.5 inches/hr
The rain stops when r = 0. So, -0.5 l t - 1 l + 0.5 = 0
l t - 1 l = 1
t - 1 = 1 or t - 1 = -1
t = 2 or t = 0
t > 0, so the rain stops when t = 2 hours