Area of a circle is
[tex]\pi {r}^{2} [/tex]
So,
[tex]\pi r {}^{2} = 1915.6826 \\ {r}^{2} = \frac{1915.6826}{\pi} \\ r = \sqrt{609.7807104} \\ r = 24.69373828[/tex]
Diameter is twice the radius. So,
24.69373838 × 2 =49.38747657
=49.4 m ( 3 significant figures) or correct the answer to the amount of significant figures the question wants