The volume ($V$) of a prism is calculated by multiplying its base area ($A$) by its height ($H$). The formula is:
$ V = A \times H $
Let the initial base area be $A$ and the initial height be $H$. The initial volume is $V = A \times H$.
The base area is increased by 25%. The new base area, $A'$, is:
$ A' = A + 0.25A = 1.25A $
The height remains the same, so the new height $H'$ is:
$ H' = H $
The new volume, $V'$, is:
$ V' = A' \times H' $
Substitute the expressions for $A'$ and $H'$:
$ V' = (1.25A) \times H $
$ V' = 1.25 \times (A \times H) $
Since $V = A \times H$, we have:
$ V' = 1.25V $
The increase in volume is:
$ \text{Increase} = V' - V = 1.25V - V = 0.25V $
To find the percentage increase in volume:
$ \text{Percentage Increase} = \frac{\text{Increase}}{\text{Original Volume}} \times 100\% $
$ \text{Percentage Increase} = \frac{0.25V}{V} \times 100\% $
$ \text{Percentage Increase} = 0.25 \times 100\% = 25\% $
Therefore, the volume increases by 25%.