Subject: General Aptitude · Chapter: Volume and Surface Area · Exam: · Marks: · Difficulty:
A rectangular water tank is $80 \mathrm{m} \times 40 \mathrm{m}$. Water flows into it through a pipe 40 sq. cm at the opening at a speed of 10 km/hr. By how much, the water level will rise in the tank in half an hour?
(a)$\frac{3}{2} \mathrm{cm}$
(b)$\frac{4}{9} \mathrm{cm}$
(c)$\frac{5}{8} \mathrm{cm}$
(d)None of these
Answer
Answer (as printed): C
Explanation
Length of water column flown in 1 min . $$=\left(\frac{10 \times 1000}{60}\right) \mathrm{m}=\frac{500}{3} \mathrm{m} .$$ Volume flown per minute $=\left(\frac{500}{3} \times \frac{40}{100 \times 100}\right) \mathrm{m}^{3}=\frac{2}{3} \mathrm{m}^{3}$. Volume flown in half an hour $=\left(\frac{2}{3} \times 30\right) \mathrm{m}^{3}=20 \mathrm{m}^{3}$. $$\text { ∴ } \text { Rise in water level }=\left(\frac{20}{40 \times 80}\right) \mathrm{m}=\left(\frac{1}{160} \times 100\right) \mathrm{cm}=\frac{5}{8} \mathrm{cm} .$$