In the figure, we can see that:
Then, the value we want, x, is the radius of a circle, and at the same time, the hypotenuse of a right triangle with legs 4.9 and 4 (half of the segment of length 8)
Then, by the pythagorean theorem:
[tex]\begin{gathered} x^2=4^2+4.9^2 \\ x=\sqrt{16+24.01}=\sqrt{40.01}=6.3253 \end{gathered}[/tex]To the nearest tenth, x = 6.33