Right, wrong, wrong, wrong, right.

British Broadcasting Corporation

Solution: Because the height is 25% less than the upper bottom, the upper bottom =80 meters, and the lower bottom = 100.

So the height =( 1- 25%), the upper bottom = 75 * 80 = 60m.

Area = (upper bottom+lower bottom) * height /2=(80+ 100)*60/2=5400 square meters.

5400*0.6=3240 kg

Give a brief answer