题目
Water has been poured into an empty rectangular tank at the rate of 5 cubic feet per minute for 6 minutes. The length of the tank is 4 feet and the width is of the length. How deep is the water in the tank? (1 foot = 12 inches)
解析
如果以每分钟5立方英尺的速度向长方体水箱注水,持续6分钟,
水箱的体积将是30立方英尺。
长方体水箱的体积公式为:\( 体积 = 长×宽×高 \)
已知:
长(\( l \))= 4英尺
宽(\( b \))= \( \frac{1}{2}×长 = \frac{1}{2}×4 = 2 \)英尺
设水箱的高为\( x \),代入体积公式:
\( 4×2×x = 30 \)
解得:\( x = \frac{15}{4} = 3.75 \)英尺 = 3英尺9英寸(因为1英尺=12英寸)(选项C)