In this question, you are given the water volume(6.2 cubic ft) and the water density (8.33 pounds/gallon). To find the water mass you need to multiply the volume with density, but you need to convert it so they have same unit.
The calculation would be:
mass = volume x density
mass = 6.2 cubic ft x 7.48 gallon/cubic ft x 8.33 pound/gallon= 386.31208 pounds.
In ounce it will be= 386.31208 pounds x 16 ounce/pouns= 6180,99328 ounces
