Answer
$\Delta{L}=1.1 cm$
Work Step by Step
We can find increase in the length as follows:
$\Delta{L}=L\alpha\Delta{T}$
For aluminum, the coefficient of linear expansion is $\alpha=23\times10^{-6}$
putting the values, we get
$\Delta{L}=33\times23\times10^{-6}\times15=0.011m$
or
$\Delta{L}=1.1 cm$
