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4道SAT数学选择题练习(二)

  下面是为大家准备的4道SAT考试数学选择题练习题。同学们在备考SAT数学的过程中,一定要加强习题的练习,熟练到能充分理解题意,争取得到满分。

  1.Miguel is180centimeters tall. At 2:00 p.m. one day, his shadow is60centimeters long, and the shadow of a nearby fence post istcentimeters long. In terms oft, what is the height, in centimeters, of the fence post?

  (A)t + 120

  (B)t over 3

  (C)3 times t

  (D)3 times (square root t)

  (E)(t over 3)^2

  2.What is the equation of the line parallel to the x-axis and four units above the x-axis? 

  (A)x = negative 4 

  (B)x = 4 

  (C)y = negative 4 

  (D)y = 0 

  (E)y = 4 

  3.The stopping distance of a car is the number of feet that the car travels after the driver starts applying the brakes. The stopping distance of a certain car is directly proportional to the square of the speed of the car, in miles per hour, at the time the brakes are first applied. If the car’s stopping distance for an initial speed of20miles per hour is17feet, what is its stopping distance for an initial speed of40miles per hour?

  (A)34feet

  (B)51feet

  (C)60feet

  (D)68feet

  (E)85feet

  4.If a, b, and care numbers such that a over b = 3and b over c = 7, then (a+b) over (b+c)is equal to which of the following? 

  (A) 7 over 2

  (B)7 over 8

  (C) 3 over 7

  (D) 1 over 7

  (E) 21 

  参考答案及解析:

  1.The correct answer is C

  Explanation

  The situation described in the question can be pictured as in the figure below, where xis the height, in centimeters, of the fence post.

 

  

math graphic

 

  There are two right triangles in the figure. One triangle is formed by part of the line from the sun to point P, the perpendicular from Miguel’s head to the ground, and Miguel’s shadow along the ground. The other triangle is formed by part of the line from the sun to point P, the perpendicular from the top of the fence post to the ground, and the fence post’s shadow along the ground. Since these two right triangles share the acute angle at P, they are similar triangles. Since the corresponding sides of similar triangles are in proportion, it follows that180 over x = 60 over t. Solving this equation for x, the height, in centimeters, of the fence post, yields x = 3 times t.

  2.The correct answer is E

  Explanation

  A line that is parallel to thex-axis and four units above thex-axis is the vertical translation of thex-axis four units upward. Since thex-axis is a horizontal line and has equationy = 0, it follows that the line parallel to thex-axis and four units above thex-axis has equationy = 4.

  3.The correct answer is D

  Explanation

  The stopping distance is directly proportional to the square of the initial speed of the car. If srepresents the initial speed of the car, in miles per hour, and drepresents the stopping distance, you have that the stopping distance is a function of sand that function d of s = c times (s^2), where cis a constant. Since the car’s stopping distance is 17feet for an initial speed of 20miles per hour, you know that 17 = c times 20^2. Therefore, c = 17 over 20^2 = 0.0425, and the car's stopping distance for an initial speed of 40miles per hour is 0.0425 times 40^2 = 68feet.

  4.The correct answer is A

  Explanation

  From a over b = 3is implied that (a+b) over b = 4(1) 

  And from b over c = 7is implied that b over (b+c) = 7 over 8(2) 

  If we multiply (1) and (2) together, we have that (a+b) over (b+c) = 4 times (7 over 8) = 7 over 2( bis canceled out).

  以上就是关于4道SAT考试数学选择题练习题及其答案和解析,非常详细。同学们在备考阶段,一定要加强习题的练习以及题意的理解,争取SAT数学满分。