28.5 g of iron shot is added to a graduated cylinder containing 45.50 ml of water. the water level rises to the 49.10 ml mark. from this information, calculate the density of iron.

Density=mass/volume.
1) we have to calculate the iron volume in liters.
iron volume=second level - first level=49.10 ml-45.50 ml=3.6 ml
3.6 ml=3.6 ml(1 liter / 1000 ml)=0.0036 liters 

2) we calculate the mass iron in kg.
28.5 g=28.5 g(1 kg /1000 g)=0.0285 kg.
2) we calculate the density of iron.
density=0.0285 kg / 0.0036 liters=7.92 kg/L

7.92 kg/l=7.92 kg/L(1000 g/1Kg)(1000 cm³/1 L)=7.92 g/cm³.

From this information the Iron density is 7.92 Kg/L or  7.92 g/cm³.