Give me the best way for solving the question of class 9^{th} of Surface areas and Volumes of exercise 13.8 of math. Give me the easiest way for solving this question in simple way of question no.3 The diameter of a metallic ball is 4.2cm. What is the mass of the ball, if the density of the metal is 8.9 g per cm3? (Assume π=22/7)

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# The diameter of a metallic ball is 4.2cm. What is the mass of the ball, if the density of the metal is 8.9 g per cm3? (Assume π=22/7) Q.3

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Given,

Diameter of a metallic ball = 4.2 cm

Radius(r) of the metallic ball, r = 4.2/2 cm = 2.1 cm

Volume formula = 4/3 πr

^{3}Volume of the metallic ball = (4/3)×(22/7)×2.1 cm

^{3}Volume of the metallic ball = 38.808 cm

^{3}Now, using relationship between, density, mass and volume,

Density = Mass/Volume

Mass = Density × volume

= (8.9×38.808) g

= 345.3912 g

Mass of the ball is 345.39 g (approx).