Water flows into a tank 180 m $$\times$$ 140 m through a rectangular pipe of 1.2m $$\times$$ 0.75 m at a rate of 15 km/h. In what time will the water rise by 4 m?

Given,

Dimensions of the tank = 180 m $$\times$$ 140 m

Dimensions of the rectangular pipe = 1.2m $$\times$$ 0.75 m

Rate of water flow = 15km/h = $$15\times\frac{5}{18}$$ m/s = $$\frac{25}{6}$$ m/s

$$\therefore\ $$Time required to rise the water by 4 m = $$\frac{180\times140\times4}{1.2\times0.75\times\frac{25}{6}}$$

$$=\frac{180\times140\times4\times6\times10\times100}{12\times75\times25}$$

$$=26880$$ sec

$$=\frac{26880}{3600}$$ hr

$$=\frac{112}{15}$$ hr

$$=7\frac{7}{15}$$ hr

$$=$$ 7 hr + $$\frac{7}{15}\times60$$ min

$$=$$ 7 hr 28 min

Hence, the correct answer is Option A