Sainik School Entrance Exam 2020 Solved Paper

Question : 20 of 150

Marks: +1, -0

Three cubes of metal whose edges are

6 {\cm}, 8 {\cm}

and

10 {\cm}

respectively are melted to form a single cube. The edge of the new cube is _________.

Solution:

(d) Volume of a cube

=(\edge)^3

∴ \V_1=(6 {\cm})^3=216 {\cm}^3

∴ \V_2=(8 {\cm})^3=512 {\cm}^3

∴ \V_3=(10 {\cm})^3=1000 {\cm}^3

On forming a single cube

\V=\V_1+\V_2+\V_3

⇒\V=216+512+1000 {\cm}^3

⇒\V=1728 {\cm}^3

⇒(\edge)^3=64 ×27=(4 ×3)^3

⇒\edge=4 ×3=12 {\cm}

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