Yellow is fake gold; it's veneer and show rather than substance. We see that with the yellow cocktail music at Gatsby's party (1) and the two girls in twin yellow dresses who aren't as alluring as the golden Jordan (3.15).
I think a moderate income is income above the median for famlies in your county, but not more than 25% of the median income. The IRS usually has this info for free, but I see they are now charging $10 for this on their web site for more recent years. http://www.irs.gov/taxstats/indtaxst...=96947,00.html.
The Urban Institute defined the middle class as adults with size-adjusted household incomes of between $30,000 and $100,000 for families of three. The Pew Research Center defines the middle-income category as including adults with family-of-three equivalent incomes between two-thirds and double the national median. This brings the range from $37,666 to $113,000 according to current levels.