Mensuration Practice Test 4

Question : 20 of 40

Marks: +1, -0

Find the percentage of wood wasted when the largest possible hemisphere is carved from a wooden cuboid with dimientions 7 × 3.5 × 3.5 cm.

Solution:

Wood wasted = Volume of cuboids - Volume of hemisphere
=

(lbh)-2/3 πr^3

= (7 × 7 × 3.5) -

(2/3 × {22}/7 × 3.5 × 3.5 × 3.5)

= 171.5 - 89.83 = 81.67
Percentage =

{81.67}/{171.5} × 100

≈ 48%

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