Question one-ga

1.1 Linear Functions - Rate of change applications
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One gallon of stain will cover 170 square feet of a surface. A yard has a total fence area of w  square feet. Which equation represents the total amount of stain S , in gallons, needed to stain the fence in this yard twice?

A.

S = w 170

B.

S = 170 w

C.

S = 340 w

D.

S = w 85

One gallon of stain will cover 170 square feet of a surface. A yard has a

Hard-difficulty · SAT Math · Linear Functions — Rate of change applications. Read the question above, select your answer, and check the full explanation below to understand exactly why the correct choice works.

Answer explanation

Choice D is correct. It's given that w represents the total fence area, in square feet. Since the fence will be stained twice, the amount of stain, in gallons, will need to cover 2 w square feet. It’s also given that one gallon of stain will cover 170 square feet. Dividing the total area, in square feet, of the surface to be stained by the number of square feet covered by one gallon of stain gives the number of gallons of stain that will be needed. Dividing 2 w by 170 yields  2w170, or w85. Therefore, the equation that represents the total amount of stain S , in gallons, needed to stain the fence of the yard twice is S=w85.

Choice B is incorrect and may result from conceptual or calculation errors.

Choice C is incorrect and may result from conceptual or calculation errors.