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Mathematics>Standard Multiple Choice

Read the following SAT test question and then click on a button to select your answer.

Caleb plans to install a patio of uniform width around a rectangular pool that measures 15 feet(ft) by 30(ft). If Caleb would like the total area of the pool and the patio to be approximately 800 ft^2 what should the approximate width of the patio be?

A.3.4ft
B.5ft
C.6.7ft
D.18.4ft

答案和解析

答案：A

解析：

Option A is correct. If x represents the uniform width, in feet, of the patio then (15+2x)(30+2x) represents the total area, in square feet, of the patio and pool combined. The problem states that this is equal to 800 square feet, so (15+2x)(30+2x)=800. This equation can be rewritten as (2x-7)(x+25)=0 and solved for the positive value of x.