Let the radius of two spheres be r1 and r2.
Given, the ratio of the volume of two spheres = 64:27
V1V2=6427⇒43πr3143πr32=6427
[∵volume of sphere=43πr3]
⇒(r1r2)3=(43)3
⇒r1r2=43
Let the surface areas of the two spheres be S1 and S2
.
∴S1S2=4πr214πr22=(r1r2)2⇒S1:S2=(43)2=169
⇒S1:S2=16:9
Hence, the ratio of their surface areas is 16:9.