jmc

The formula for the area of a triangle is $\frac{1}{2}\text{base}\times \text{height}$. Using this, we can find the length of $AB$, because we know the area of triangle $ABE$. $$6=\frac{1}{2}AB\times 4$$$$12=AB\times 4$$$$AB=3$$Since $AB=BC=CD$, $AC=2\times AB=6$.

To find $CE$, use the Pythagorean Theorem, treating $CE$ as the hypotenuse of triangle $ACE$. $$4^2+6^2=C{E}^2$$$$C{E}^2=52$$Then $CE=\sqrt{52}.$ Rounded to the nearest tenth, this is $\boxed{7.2}.$