The cost, C, in United States Dollars ($), of cleaning up x percent of an oil spill along the Gulf Coast of the United States increases tremendously as x approaches 100. One equation for determining the cost (in millions $) is:

Complete Question

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The value of k is  

The percentage  of the oil that will be cleaned is

Step-by-step explanation:

From the question we are told that

   The  cost of cleaning up the spillage is    

     The  cost of cleaning x =  70% of the oil is  

Now at   we have  

Now  When  

w^2 + 70w + 2450 = 8450

w^2 + 70w - 6000 = 0

.

Factoring the left:

(w-50)(w+120) = 0

.

w = {-120, 50}

.

toss out the negative solution:

width is 50 feet

length is 50+70= 120 feet