There's a new version of Kellogg's Raisin Bran: It contains sweetened dried cranberries as well as raisins. The box appears to be the same size as the 18.7-ounce box of regular Kellogg's Raisin Bran, and it sells for $3.05, just a tick more than the $2.94 for the box of regular Raisin Bran. But though the boxes are essentially the same in height and width, the new item's box is notably less thick, which helps explain why it contains just 13.5 ounces instead of 18.7. (For comparison, a hypothetical 13.5-ounce box of regular Kellogg's Raisin Bran, at the per-ounce price of the $2.94 18.7-ounce box, would cost just $2.12 — 93 cents less.) So the with-cranberries version costs 44 percent more per ounce.
In fairness, Mr. Tidbit must acknowledge that the presence of the costlier cranberries in the new cereal is surely a factor in the higher price. To assess how much of the extra 93 cents (for 13.5 ounces of cereal) is cranberry-related, he bought the 18.7-ounce box of Raisin Bran and the 13.5-ounce box of Raisin Bran with cranberries, and he weighed the raisins and cranberries on his kitchen scale.
The 18.7-ounce box of regular Kellogg's Raisin Bran contained 5.3 ounces of raisins. (So the hypothetical 13.5-ounce box of regular raisin bran would contain 3.8 ounces of raisins.) The 13.5-ounce box of Kellogg's Raisin Bran with Cranberries contained 1.5 ounces of raisins and 1.8 ounces of cranberries, for a total of only 3.3 ounces.
At the discount store where Mr. Tidbit purchased the cereals, a 10-ounce bag of Sun-Maid raisins was $2.74 (27.4 cents per ounce), and a 10-ounce bag of Ocean Spray craisins was $2.99 (29.9 cents per ounce). At those prices, the raisins in the 13.5-ounce hypothetical box of regular raisin bran would cost $1.04. The raisins and cranberries in the with-cranberries box would cost a total of 95 cents. So — because the total amount of fruit is smaller, even if some of it is cranberries — the fruit in the with-cranberries box costs 9 cents less than the raisins in the same amount of just-raisins cereal.
Summing up: The box of the new cereal costs 93 cents more than the regular cereal — and it contains 9 cents' worth less fruit.