Q.If the ratio of the volume of a sphere with radius ???? to the volume of a cone with the same radius is 4:9, then the height of the cone will be.. (a) \(3r\) (b) \(4r\) (c) \(6r\) (d) \(9r\)
Answer: A
Let the height of the cone be \(h\) units. \[ \therefore \frac{4}{3}\pi r^3 : \pi r^2 h = 4 : 9 \] Or, \[ \frac{4}{3}r : h = 4 : 9 \] Or, \[ \frac{4r}{3h} = \frac{4}{9} \] So, \[ 12h = 36r \] Therefore, \[ h = 3r \]
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