A copper wire having length of 243m and diameter 4 mm was melted to form a sphere. Find the diameter of the sphere :
Volume of copper wire melted will be equal to volume of sphere.
Volume of copper wire = Area $$\times\ $$ length = $$\pi\ \left(\frac{2}{10}\right)^2\times\ 24300\ cm^3$$
Let the radius of sphere be r
$$\frac{4}{3}\pi\ r^{3\ \ }=\ \pi\ \left(\frac{2}{10}\right)^2\times\ 24300\ cm^3$$
$$r^3$$ = 729
r = 9 cm
Diameter of sphere = 2(9) = 18 cm
Answer is option B.
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