No big deal
When you buy a large can of tuna, chances are there's something fishy. A Purdue University study found that two 6-ounce cans of tuna are usually cheaper than one 12-ounce can.
The pricing is called "surcharging." It happens because consumers who buy "economy-size" packages have a mistaken belief that big sizes are always cheaper per ounce and they don't bother to examine the prices. So manufacturers or grocery stores sometimes take advantage of this inattention, the researchers say.
Other products that often cost less in smaller sizes include toilet paper, canned chili, peanut butter, and ketchup.
Source: Purdue University
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