prep 数学一道，不大理解题意。

carolcai

90.   10132-!-item-!-187;#058&007125

A circular jogging track forms the edge of a circular lake that has a diameter of 2 miles.  Johanna walked once around the track at the average rate of 3 miles per hour.  If t represents the number of hours it took Johanna to walk completely around the lake, which of the following is a correct statement?

(A) 0.5 < t < 0.75

(B) 1.75 < t < 2.0

(C) 2.0 < t < 2.5

(D) 2.5 < t < 3.0

(E) 3 < t < 3.5

题目到底是想求什么呢？我做的就是周长除以速度。怎么会有不等式出现啊？

[此贴子已经被作者于2008-7-5 15:56:25编辑过]

shiverson

直径2的湖（圆），速度3，走一圈多长时间，即求周长

pie*d=2pie约等于6.28     再除以3           C

carolcai

哦，原来是这样