Question

# A cylindrical jar of radius 12 cm contains oil. Iron spheres each of radius 3 cm are immersed in the oil. How many such spheres are needed to raise the oil by 4 cm?16 8 10 32

Solution

## The correct option is A 16 Note that, Volume of the cylinder with height  4 cm = n× Volume of one iron sphere, where n is the required number of iron spheres. Let R and r be the radii of the cylindrical jar and the iron sphere respectively. i.e., R=12 cm and r=3 cm Then we have,πR2h=n×43π×r3 ⟹π122×4=n×43π×33 ⟹n=16 ​

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