6.3 SAT Math - Data Analysis

There will be other graphs on the SAT exam that are not necessarily linked or related to functions.  These questions may have a function that goes with them, but more likely they will simply be based on the information presented. 
-SAT Math Hint: Most data analysis questions are testing your ability to read carefully and notice details.  Be sure you do both of these things in order to get them right.

Most charts or graphs simply want you to compare a few key pieces of information.  Take a look at this one:

11. Based on the graph shown above, on what day did Sam's Shirts and Tony's Tees have the greatest difference in sales?
(A) Monday (B) Tuesday (C) Wednesday (D) Thurday (E) Friday

For this question, you simply need to determine at which point the two company's sales were the farthest apart on the graph.  Based on how the graph looks, it appears Thursday or Friday should be the answer. 
-SAT Math Hint: Do NOT simply take a good guess based on how it looks!  If it is unclear in a graph exactly what the values are you need to work with, use your answer sheet as a ruler to line up the markers with the values.  Remember: these questions are testing your attention to detail, so don't speed through just to get it done.

If you line up the values and subtract, you'll find that Thursday's difference is 11, while Friday's difference is 12, so Friday is the answer.

Most data analysis questions are pretty straightforward as long as you read carefully.  The only one that tends to sometimes give people trouble is a scatterplot:

A scatterplot shows data that deals with variables that relate to the same event.  Scatterplots on the SATs will occasionally ask you to use the data presented, and in those cases, you'll simply use the information they way you would for any other chart, keeping in mind that each value in a column relates to the same variable (in the scatterplot above, as an example, all the dots in column 1 related to 1 dog owned, all the dots in column 2 related to 2 dogs owned, etc.)  The tricky part about scatterplots is more often when you're asked to find a trend line, or a "line of best fit."  This sounds confusing, but it's not that difficult.  You do NOT want to draw a line connecting the dots.  The line you want to draw should be up the middle of the points, that is, you want to have about half the points above your trend line and have your points below the trend line.  The trend line can help you predict future results, so if the question accompanying this graph were "Approximately how much would someone with six dogs expect to spend per year on veterinary bills?" you can make a reasonable choice based on the trend line.

(A) 200 (B) 230 (C) 350 (D) 500 (E) 700

The best answer here is (C) 350.