[tex]\huge\underline{\red{A}\blue{n}\pink{s}\purple{w}\orange{e}\green{r} -}[/tex]
We know that ,
[tex]\bold{Volume \: of \: cone = \frac{1}{3}\pi \: r {}^{2} h }\\ [/tex]
substituting the values in the formula stated above ,
[tex]\bold{769.3 = \frac{1}{3} \times 3.14 \times r {}^{2} \times 15} \\ \\\bold{\implies r {}^{2} = \frac{769.3 \times 3}{3.14 \times 15} } \\ \\\bold{\implies r {}^{2} = \cancel\frac{2307.9}{47.1}} \\ \\\bold{ \implies \: r {}^{2} = 49} \\ \\ \bold{\implies \: r = 7 \: ft}[/tex]
therefore ,
radius = 7 cm
hope helpful ~