Question Details

A hemispherical storage vessel having a total surface area of 1323π sq cm is filled to capacity with cooking oil. The entire quantity of oil is transferred into a cylindrical drum of the same radius, filling it completely. What is the height of the cylindrical drum?

Options

A

18 cm

B

28 cm

C

21 cm

D

14 cm

E

10 cm

Show Answer

Correct Answer :

Option D

14 cm

Solution :

The correct option is 14 cm.

Step 1: Find the radius of the hemispherical storage vessel.

The total surface area of a hemisphere of radius r is given by the formula:

Total Surface Area = 3πr2

Given that the total surface area is 1323π cm2:

3πr2=1323π

Dividing both sides by 3π:

r2=441

Taking the square root of both sides:

r=441=21 cm

Step 2: Relate the volume of the hemispherical vessel to the cylindrical drum.

The volume of cooking oil in the hemispherical vessel filled to capacity is:

Volume of Hemisphere = 23πr3

Since the entire quantity of oil is transferred into a cylindrical drum of the same radius r and height h, filling it completely, the volume of the cylindrical drum equals the volume of the hemisphere:

Volume of Cylinder = πr2h

Equating the two volumes:

πr2h=23πr3

Dividing both sides by πr2 simplifies to:

h=23r

Step 3: Calculate the height of the cylindrical drum.

Substitute r=21 cm into the height expression:

h=23×21=14 cm

Thus, the height of the cylindrical drum is 14 cm.

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