The volume of two spheres are in the ratio of 64 : 27. The ratio p their surface areas is :
A. 1 : 2
B. 2 : 3
C. 9 : 16
D. 16 : 9
Answer: Option D
Solution(By Examveda Team)
Let their radii be R and rThen,
$$\eqalign{ & \frac{{\frac{4}{3}\pi {R^3}}}{{\frac{4}{3}\pi {r^3}}} = \frac{{64}}{{27}} \cr & \Rightarrow {\left( {\frac{R}{r}} \right)^3} = \frac{{64}}{{27}} \cr & \Rightarrow {\left( {\frac{R}{r}} \right)^3} = {\left( {\frac{4}{3}} \right)^3} \cr & \Rightarrow \frac{R}{r} = \frac{4}{3} \cr} $$
Ratio of surface areas :
$$\eqalign{ & = \frac{{4\pi {R^2}}}{{4\pi {r^2}}} = {\left( {\frac{R}{r}} \right)^2} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = {\left( {\frac{4}{3}} \right)^2} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \frac{{16}}{9} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 16:9 \cr} $$
Related Questions on Volume and Surface Area
A. 12$$\pi$$ cm3
B. 15$$\pi$$ cm3
C. 16$$\pi$$ cm3
D. 20$$\pi$$ cm3
In a shower, 5 cm of rain falls. The volume of water that falls on 1.5 hectares of ground is:
A. 75 cu. m
B. 750 cu. m
C. 7500 cu. m
D. 75000 cu. m
A. 84 meters
B. 90 meters
C. 168 meters
D. 336 meters
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