Answer
1.09 V
Work Step by Step
The cell made up of $Zn/Zn^{2+}$ and $Cu/Cu^{2+}$ half-cells is the Daniel cell. For the Daniel cell, the Nernst equation at $25^{\circ}$ is
$E=1.10\,V-\frac{0.0257\,V}{2}\ln\frac{[Zn^{2+}]}{[Cu^{2+}]}$
$=1.10\,V-\frac{0.0257\,V}{2}\ln\frac{0.25\,M}{0.15\,M}=1.09\,V$
