We know that 1m=100cm
Dimension of the tank is 1.05m and 70cm and 1.5cm.
Also we know that volume of cuboid = length × breadth × height
V = 105 × 70 × 1.5
V = 11025cm3
And we know that 1cm3= 8 grams
Weight of iron piece = 11025 × 8 = 88200g
But 1kg=1000g
Weight of iron piece = 88.2kg