SajjadAhmad
One hose dispenses water at the rate of one gallon per minute, and a second hose dispenses water at the rate of \(1\frac{1}{2}\) gallons per minute. At the same time, the two hoses begin filling a cylindrical pail whose diameter is 14 inches and whose height is 10 inches. Which of the following most closely approximates the water level, measured in inches up from the pail’s circular base, after \(1\frac{1}{2}\) minutes? [231 cubic inches = 1 gallon]
(A) 3.5
(B) 4.2
(C) 4.8
(D) 5.6
(E) 6.7
Solution:
• Total water dispensed in one minute = \(1 + \frac{3}{2} =\frac{5}{2}\) gallons
o Total water dispensed in 1 \(\frac{1}{2}\) minute = \(1 \frac{1}{2}*\frac{5}{2} =\frac{15}{4}\) gallon
o Total water dispensed in inch = \(\frac{15}{4 }*231\) cubic inch
• Radius of the tank = \(\frac{diameter}{2} = \frac{14}{2} = 7\) inch
Note: - Radius of the tank will remain same, but the height of the water level will depend upon the water poured in the tank.
Let h be the level of water in the tank after pouring \(\frac{15}{4 }*231\) cubic inches of water.
• Volume of tank till the height \(h = π*r^2*h\)
o \(\frac{15}{4 }*231 = \frac{22}{7}*7*7*h\)
o \(\frac{(15*231)}{(4*22*7)} = h\)
o\(\frac{(15*3)}{(4*2)} = h\)
o \(h = 5.625\) (approx.)
Hence, the correct answer is
Option D.