dimension analsis

Question

Each year, approximately (1.8 x 10⁷ bales or 9.0 x 10⁸ lb) of cotton are harvested in the United States. A field planted with cotton can produce 7.0 x 10² lb for each acre of land. The fabric obtained from each bale can produce roughly 750 pairs of denim jeans. If you need to produce 10 000 pairs of jeans how many bales of cotton would you need to harvest?

Answer 1

To do these kind of problems, you need to start with an extensive quantity (Something that determines how much) and you need relationships between units of a particular quantity (conversion factor) or anything that ties two quantities for our particular problems(any equality or ratio that applies, like a density or molarity - pseudoconvergence factors)

10000 Jeans --> bales has a direct conversion and all the other information is noise:

10000 Jeans (1 bale/ 750 Jeans) - 13.3 bales

A better question would have been, "How many acres of land are required to make 10,000 jeans?"

Take care.