SAT数学之文字题解题方法

2017年07月31日15:01 来源：互联网: 参与（0）阅读（4505）

摘要：改革之后SAT数学的趋势就是很多真题又长又臭，很多同学花了大量的时间在阅读真题上，但是读了一遍又一遍，可能还是what 脸？数学到底考的是数学还是阅读啊？？！！

今天我们便来细看一下文字题到底该如何解答，大体的原则是从后往前读，而不是从前往后读

文字题读什么?

1.question

2.图表横纵坐标表示变量以及单位度量

3.题目中的数字，比较关系，倍数关系

4.单位换算以及四舍五入

来两个例子~~~

Typically, when people contract an infectious disease, their immune system immediately begins to produce extra white blood cells to fight the disease. The scatterplot shows the white blood cells reproducing in an infected patient, along with several values found when modeling the data using a graphing calculator. According to this model, how many white blood cells per microliter of blood did the patient have before he contracted the disease?

(A) 3,400

(B) 8,500

(D) 13,600

分析：问题是：contract the disease 前对应的white blood cells per microliter of blood数量，所以应该求t = 0 时Blood cell数量。图表反应的是：感染病人体内white blood cells同hour的变化关系，呈现上升趋势，并且纵坐标单位为thousands per mcl。结合上升趋势以及table中给出数据判断出为exponential growth model，每过一个小时白细胞数量变成原来两倍。此题特殊之处在于原点并非t = 0 时对应的初始值，所以还要往前推。t = 4, y = 136，所以t = 3, y = 68依次推得：t = 0 , y = 8.5 结合纵轴单位度量，答案为8500。

所以此题结合问题以及图示就可以得出答案，不需要重读前面的背景部分。

An occupational health organization published a study showing an increase in the number of injuries that resulted from elderly people falling in the bathtub. In response to this increase, a medical supply company decided to drop its price on bathtub lifts from $450 to $375, hoping to still break even on the lifts. The company breaks even when its total revenue (income from selling n bathtub lifts) is equal to its total cost of producing the lifts. If the cost C, in dollars, of producing the lifts is C = 225 n + 3,150, how many more of the lifts does the company need to sell at the new price to break even than at the old price?

(A) 7 (B) 12 (C) 14 (D) 21

分析：观察问题： how many more of the lifts does the company need to sell at the new price to break even than at the old price?所以是一题减法题。涉及到一个经济学词汇“break even”，向前扫读有解释：total revenue (income from selling n bathtub lifts) is equal to its total cost of producing the lifts 所以意思是收入 = 成本，所以问题问的是新价格下盈亏相抵要比旧价格下盈亏相抵多卖多少电梯。成本公式为 C = 225 n + 3,150

扫读背景中的数字为价格从450下降为375，可设原价为a, 新价为b，列式：

450a = 225 a + 3,150 375b = 225 b + 3,150 解得： a = 14, b= 21

最终答案为a – b = 7 选 A

所以同学们有了解到文字题的读题顺序以及注意事项吗?最主要的是克服恐惧心理，多练习读题方法，而不是一遍遍读题。