标题: GWD 25 33 沒人問過 [打印本页] 作者: Kath1985 时间: 2010-6-26 22:18 标题: GWD 25 33 沒人問過 Q33. A pump started filling an empty pool with water and continued at a constant rate until the pool was full. At noon the pool was 1/3 full, and 1+1/4 hours later it was 3/4 full. What was the total number of hours that it took the pump to fill the pool? A. 2+1/3 B. 2+2/3 C. 3 D. 3+1/2 E. 3+2/3
答案C
請問這題要如何解呢 ? 作者: yvonne880919 时间: 2010-6-26 22:51
X is the totall water
so it takes 1+1/4 hours to finish (3/4-1/3) X water
(3/4-1/3)X/(1+1/4)=1/3 X water per hour
so the time to fill the pool is X/ (1/3 X)=3作者: gchgeng 时间: 2010-6-26 22:53
先用3/4减去1/3，即 5/4小时充了5/12的水， 用5/12除以5/4算出一小时可充满水池的1/3，所以三小时可以充满。这么说行吗？作者: Kath1985 时间: 2010-7-5 11:01
hum 懂了 只要遇到這種題目 先算出一小時的單位量 對吧