One cubic feet of sand wounds 100 lbs. a square sandbox with 5 foot sides had half of a foot of sand in it. how many lbs of sand is in the sandbox?

Ok so find volume of sandbox
v=area of base times height
height=1/2
area of base=a square=side^2=5^2=25
so
v=1/2 times 25=12.5 ft^3
12.5 cubic feet
1 cubic foot=100lb
12.5 times 1cubic foot=100lb times 12.5
12.5 cubic feet=1250lb

answer is 1250 lb