请问一道 PP T1 PS # 182

Stock    Numbers of the share

-------     ------------------------------

  V                   68

  W                 112

  X                   56

  Y                   94

  Z                   45

The table shows the number of shares of each of the 5 stocks owned by Mr. Sami.  If Mr. Sami was to sell 20 shares of Stock X and buy 24 shares of Stock Y, what would be the increase in the range of the numbers of shares of the 5 stocks owned by Mr. Sami?

(A) 4

(B) 6

(C) 9

(D) 15

(E) 20

请帮忙解惑

 range before=112-45=67

range after=(94+24)-(56-20)=82

so increase in range=82-67=15

 range=largest number-least number

感谢
            …原来这么简单