The ratio of the diameters of two circles is 15:19. Find the ratio of their circumferences.

Given,

The ratio of the diameters of the circle = 15:19

Let the diameter of the first circle be ${\mathrm{d}}_1 = 15\mathrm{x}$

The diameter of the second circle be ${\mathrm{d}}_2= 19\mathrm{x}$

So, the ratio of circumferences of two circles$={\mathrm{\pi d}}_1:{\mathrm{\pi d}}_2=\mathrm{\pi }\times 15\mathrm{x}:\mathrm{\pi }\times 19\mathrm{x}=15:19$.