Subject: General Aptitude · Chapter: Volume and Surface Area · Exam: · Marks: · Difficulty:
The water in a rectangular reservoir having a base 80 m by 60 m is 6.5 m deep. In what time can the water be emptied by a pipe of which the cross-section is a square of side 20 cm, if the water runs through the pipe at the rate of 15 km per hour?
(a)26 hrs
(b)42 hrs
(c)52 hrs
(d)65 hrs
Answer
Answer (as printed): C
Explanation
Volume of water in the reservoir $=(80 \times 60 \times 6.5) \mathrm{m}^{3}$ $$=31200 \mathrm{m}^{3} .$$ Volume of water flowing out per hour $$=\left(15000 \times \frac{20}{100} \times \frac{20}{100}\right) \mathrm{m}^{3}=600 \mathrm{m}^{3} .$$ ∴ Total time taken to empty the $\operatorname{tank}=\left(\frac{31200}{600}\right) \mathrm{hrs}=52 \mathrm{hrs}$.