Answer: 108 lbs.
Explanation:
Given : A cube is packed with decorative pebbles. If the cube has a side length of 6 inches.
Volume of cube =

i.e. Volume of cube =

Since , each pebble weighs on average 0.5 lb per cubic inch.
Then, the total weight of the pebbles in the cube will be
= 0.5 x Volume of cube
=

Hence, the total weight of the pebbles in the cube =108 lbs.