1210 cubic feet
Explanation:
Initial dimensions of the storeroom were
length,
width and
height.
The room is in the shape of a cuboid. Volume of a cuboid =
, where
are the length, width and height of the cuboid.
So, Volume of storeroom initially =

Finally, the length was increased to
and width to
.
Final volume of storeroom =

Increase in volume =

∴ 1210 cubic feet of storage was added.