A bucket contains 200 cc of liquid. A solid ball is dropped in the bucket resulting in the rise of liquid level to 1.3 times of its original level. If the radius of the base of the bucket is 3 cm and the radius of the surface of the liquid level is 1 cm more than the radius of the base of the bucket before the ball is dropped. Find the volume of the solid metal ball.
Explanation:
The radius of the bucket is 3 cm and the radius of the original water level is (3 + 1) = 4 cm
Original volume = 200 cc
Let the original height of water = h cm
Using the formula for volume of frustum of cone:
200=h3π[42+32+(4)(3)]
∴ h = 600/37π
Now, the height of the liquid increases by 0.3 times itself i.e. it becomes 1.3h
In a frustum of cone, ratio of radii is the same as ratio of heights (applying the concepts of similarity).
∴ New radius = 4.3 cm
∴ Volume of ball = new volume – original volume
=1.3h3π[4.32+32+(4.3)(3)]-200
=1.3h3×π×60037π×40.4-200
= 283.9 - 200 = 83.9 cc
The closest value in the options is 80 cc.
Hence, option (b).
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