We can solve it with the formula V = hπr² Substitute the volume, height, and of course, the pi. Therefore, we'll have this equation.

V=h \pi r^2\\1416.93dm^3=(5dm)(3.14)(r^2)\\1416.93dm^3=(15.7dm)(r^2) \\ \frac{1416.93dm^3}{15.7dm} = \frac{(15.7dm)(r^2)}{15.7dm}\\ \sqrt{90.25dm^2}= \sqrt{r^2} \\9.5dm=r

The answer to your question is 9.5 dm. 

I'm not sure 'bout my answer, but please, kindly correct me if I'm wrong. ^_^

Same question here, by the way >> <<
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I want those points, anyway. Hehehe ^-^
you got the points, and stars :-)