10111.11\(_{two}\) 

convert the number to base 10.

10111.11\(_{two}\) = 1 x 2\(^4\) + 0 x 2\(^3\) + 1 x \(^2\) + 1 x 2\(^1\) + 1 x 2\(^0\) + 1 x 2\(^{-1}\) + 1 x 2\(^{-2}\)

= 16 + 0 + 4 + 2 + 1 + \(\frac{1}{2}\) + \(\frac{1}{4}\)

= 23 + \(\frac{3}{4}\) = 23\(\frac{3}{4}\)