SAT數學之文字題解題案例分析
來源：互聯網
小編：天空 595今天我們便來細看一下文字題到底該如何解答，大體的原則是從后往前讀，而不是從前往后讀
文字題讀什么?
1.question
2.圖表 橫縱坐標表示變量以及單位度量
3.題目中的數字，比較關系，倍數關系
4.單位換算以及四舍五入
來兩個例子~~~
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
(C) 10,000
(D) 13,600
分析：問題是：contract the disease 前對應的white blood cells per microliter of blood數量，所以應該求t = 0 時Blood cell數量。圖表反應的是：感染病人體內white blood cells同hour的變化關系，呈現上升趨勢，并且縱坐標單位為thousands per mcl。結合上升趨勢以及table中給出數據判斷出為exponential growth model，每過一個小時白細胞數量變成原來兩倍。此題特殊之處在于原點并非t = 0 時對應的初始值，所以還要往前推。t = 4, y = 136，所以t = 3, y = 68依次推得：t = 0 , y = 8.5 結合縱軸單位度量，答案為8500。
所以此題結合問題以及圖示就可以得出答案，不需要重讀前面的背景部分。
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：觀察問題： how many more of the lifts does the company need to sell at the new price to break even than at the old price?所以是一題減法題。涉及到一個經濟學詞匯“break even”，向前掃讀有解釋：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，所以問題問的是新價格下盈虧相抵要比舊價格下盈虧相抵多賣多少電梯。 成本公式為 C = 225 n + 3,150
掃讀背景中的數字為價格從450下降為375，可設原價為a, 新價為b，列式：
450a = 225 a + 3,150 375b = 225 b + 3,150 解得： a = 14, b= 21
最終答案為a – b = 7 選 A
所以同學們有了解到文字題的讀題順序以及注意事項嗎?最主要的是克服恐懼心理，多練習讀題方法，而不是一遍遍讀題。
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