Scott Woodbury-Stewart

GMAT OFFICIAL GUIDE PS – The cost C, in dollars, to remove p…

The cost C, in dollars, to remove p…

Solution:

The cost to remove 90 percent of the pollutant is determined by letting p = 90 in the cost formula:

100,000(90)/(100 – 90) = 9,000,000/10 = 900,000

Similarly, the cost to remove 80 percent of the pollutant is determined by letting p = 80 in the cost formula:

100,000(80)/(100 – 80) = 8,000,000/20 = 400,000

To determine how much more it costs to remove 90 percent of the pollutant than 80 percent of the pollutant, we calculate the difference of the two costs:

900,000 – 400,000 = 500,000

Answer: A 

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