3 2 ÷[(1- 1 2 )×(1- 1 2 )×(1- 1 2 )×(1- 1 2 )×(1- 1 2 )]= 3 2 ÷[ 1 2 × 1 2 × 1 2 × 1 2 × 1 2 ]= 3 2 ÷ 1 32 =48(千克)答:这块冰原来的重量是48千克.