GRE考试

【单选题】In 1980, the cost ofp pounds of potatoes was d dollars. In 1990, the cost of 2p pounds of potatoes was
dollars.By what percent did the price of potatoes decrease from 1980 to 1990
A、25%
B、50%
C、75%
D、100%
E、400%
网考网参考答案：C
网考网解析：
Since, in 1990, 2p pounds of potatoes cost [*] dollars, p pounds cost half as much: [*][*] or 25%, as much as the cost in 1980, which represents a decrease of 75%. **In this type of problem it is often easier to use TACTIC 2, Chapter 11. Assume that 1 pound of potatoes cost $100 in 1980. Then in 1990, 2 pounds cost $50, so 1 pound cost $25. This is a decrease of $75 in the cost of 1 pound of potatoes, and [*] document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>