Answer:
674.2 lb
Step-by-step explanation:
(5 ft)·(8 ft)·(1.2 in)·(12 in/ft)²·(2.54 cm/in)³·(2.7 g/cm³)/(453.592 g/lb) ≈ 674.2 lb
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Comment on units conversion
Units conversion is easily done using conversion factors that have a value of 1. That is, the value of the numerator is equal to the value of the denominator. (12 in = 1 ft, for example). The numerator units are chosen to match units you want, while the denominator units are chosen to match units you want to cancel.
Here, we convert in³ to cm³ to lb using conversion factors given and ones we know.
