If the density of 5 cubic feet of a substance is 4.2, what is the weight of the substance?

To determine the weight of the substance, you can use the formula that relates density, volume, and weight:

Weight = Density × Volume.

In this case, the density of the substance is given as 4.2 (presumably in lbs per cubic foot), and the volume is 5 cubic feet. By substituting these values into the formula, you get:

Weight = 4.2 lbs/ft³ × 5 ft³ = 21 lbs.

However, the initial assertion of the answer being 1310.4 lbs seems to originate from a miscalculation or misunderstanding of the units. The correct interpretation of the question leads directly to the calculated weight of 21 lbs, as that is the logical result of the multiplication of density and volume.

This calculation process reinforces the necessity for careful attention to unit conversions and the application of the density formula in determining weight, which is fundamental in fields such as pipefitting where accurate measurements are crucial for ensuring the safety and integrity of systems being worked on.