A 5.0 gram sample of lead and a 3.2 gram sample of iron are placed into 367 mL of water. What will be the new volume level of water in units of mL? The density of lead is 11.34 g/cc and the density of iron is 7.874 g/cc. Round your answer to three significant figures.

Density is dependent on mass and volume of a substance and can be defined as the ratio of mass to volume. In other words:
density = mass/volume
or
volume = mass/density
In this case, we need to determine the volume of added lead and iron to figure out the final volume of the water sample.
Volume of lead = mass of lead / density of lead = 5 gm / 11.34 g/cc = 0.441 cc or 0.441 ml
Similarly, volume of iron = mass of iron / density of iron = 3.2 g / 7.874 g/cc
= 0.406 cc or 0.406 ml
The new volume of water sample = original volume of water + volume of lead + volume of iron = 367 ml + 0.441 ml + 0.406 ml = 367.847 ml
To the 3 significant figures and without the unit (ml), the answer is 368.
Hope this helps.