Question: A cylinder whose height is $ \frac{2}{3} $ of its diameter has same volume as that of a sphere of radius 8 cm. The radius of base of the cylinder is
Options:
A) 8 cm
B) 4 cm
C) 2 cm
D) 5 cm
Show Answer
Answer:
Correct Answer: A
Solution:
- [a] Height of the cylinder $ =\frac{2}{3}\times $ [Diameter of sphere
Height $ =\frac{4\times Radius}{3} $ [ $ \because $ Diameter $ =2\times $ Radius]
Volume of sphere $ =\frac{4}{3}\pi \times {{(8)}^{3}} $
Now, volume of cylinder $ =\pi r^{2}\times h=\pi \times r^{2}\times \frac{4r}{3} $
$ \Rightarrow $ $ \frac{4}{3}\times \pi \times {{(8)}^{3}}=\pi \times r^{2}\times \frac{4r}{3} $
$ \Rightarrow $ $ 4\times 512=4r^{3} $
$ \Rightarrow $ $ r=8,cm $
Alternate Method
Height of the cylinder $ =\frac{4}{3}\times Radius $
Hence, radius of the sphere and cylinder are same i.e. 8 cm.