A pen stand made of wood is in the shape of a cuboid with four conical depressions to hold pens. The dimensions of the cuboid are 15 cm by 10 cm by3.5 cm. The radius of each of the depressions is 0.5cm and the depth is 1.4 cm. Find the volume of wood in the entire stand (see Fig. 13.16)
Given:
Depth (h) of each conical depression = 1.4 cm
Radius (r) of each conical depression = 0.5 cm
Volume of wood = Volume of cuboid - 4 × Volume of cones
= lbh – 4 * 
r2h
= 15 * 10 * 3.5 – 4 * 
* 
* (
)2 * 1.4
= 525 – 1.47
= 523.53 cm3
Hence,
The volume of wood in the entire stand= 523.53 cm3
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