As I think the original request was for common behaviors that can be related to psychological topics, I think the question of how one figures a standard tip is also interesting. I see people using little "tip tables" that give 15% of various amounts in table form, but without such a table, how one represents the problem can make a big difference in problem difficulty. We're taught to figure things like this by multiplying the total bill by .15, and we're taught to do problems like that using a complicated algorithm* that amounts to manipulation of symbols. That algorithm is too complicated for most of us to do mentally, without at least writing down intermediate answers, something which is often not possible when figuring a tip (due to lack of pencil and paper).
But there are other ways to figure 15% besides that kind of symbol manipulation. I usually figure 10% (simply by moving over the decimal point mentally), and then figure (again, mentally) half of that number (which is then 5% of the total), and then (yet again mentally) add the two. Alternatively, one could figure 10%, and then 20% (simply by doubling the 10%) and then figure the halfway mark between those two numbers (I haven't used that method, and I don't know if it would be too taxing for me). I'll bet there are other ways that people use besides these, and I'd think they might lead to an interesting discussion of the role of mental representation in mathematical problem solving. Most Introductory texts have a chapter on "Language, Thinking, and Problem Solving" where the relevant material would be found. I suspect that most of the people who still try to use the symbol manipulation algorithm in the tipping context also believe that symbol manipulation method they've been taught IS multiplication, and don't realize that it's just one of many devices for finding the answer to multiplication problems. * "Okay, class, remember, start by multiplying the ones column, and write your answer below the ones column, carrying any tens you get up to the top of the tens column. Then take the tens column from the first multiplicand times the ones column from the second..." Paul Smith Alverno College Milwaukee --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]
