GWD 25 33 沒人問過

Kath1985

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 ?

yvonne880919

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

gchgeng

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？

Kath1985

hum 懂了  只要遇到這種題目 先算出一小時的單位量 對吧