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Probability

Question
CBSEENMA9003716

Three solid spheres of iron whose diameters are 2 cm, 12 cm and 16 cm respectively are melted into a single solid sphere. Find the radius of the solid sphere. 

Solution

Let the radius of the solid sphere be R cm.
Then, according to the question,
4 over 5 πR cubed equals 4 over 3 straight pi open parentheses 2 over 2 close parentheses cubed plus 4 over 3 straight pi open parentheses 12 over 2 close parentheses cubed plus 4 over 3 straight pi open parentheses 16 over 2 close parentheses cubed
rightwards double arrow space space space straight R cubed equals 1 plus 216 plus 512
rightwards double arrow space space space straight R cubed equals 729 equals 9 cubed
rightwards double arrow space space space straight R space equals space 9 space cm
Hence, the radius of the solid sphere is 9 cm.