Graphs, Charts, and Tables
Graphs, Charts, and Tables
There are countless ways to organize and present data. Luckily, the SAT uses only three of them: graphs, charts, and tables. On easy graphs, charts, and tables questions, the SAT just tests to see if you can understand the data being presented. More complicated questions ask you to perform some type of operation on data found in a chart or graph, such as calculating a mean or a percent.
Simple Charts, Graphs, and Tables Questions
Reading charts and graphs questions is pretty straightforward. The SAT shows you a chart. You answer a question about the data in the chart.
In the following bar graph, the greatest change in the net income of Joe’s Lemonade Stand occurred between what two months?
Maybe you looked at this question and realized that you didn’t know what the term “net income” means. Well, whether you did or didn’t know the term, it doesn’t matter. The graph tells you that the bars represent net income; you don’t have to know what net income is to see between which months the net income differed most.
For this graph, a quick look makes it clear that the two biggest differences in terms of net income per month are between April and May, and between February and March. The net income in April was $20 and the net income in May was $50, making the April–May difference $30. The net income in February was $30 and the net income in March was –$10, so the February–March difference was $40. The answer, therefore, is February to March. This question throws a tiny trick at you by including negative numbers as net income. If you don’t realize that March is negative, then you might choose the April–May difference.
When dealing with graphs and charts, be sure to pay attention to negative and positive values. And ignore distracting information—like the meaning of net income—that makes easy questions seem complex.
Performing Operations on Data
The second type of charts and graphs question asks you to take a further step. You have to use the data in the chart or graph to perform some operation on it. For instance, you could be asked to figure out the mean of the data shown in a graph. Or, you could be asked something like this:
What was the percent increase in the net income from April to May?
To find the percent increase in net income from April to May, you have to find out how much the net income increased between April and May and then compare that increase to the original net income in April. The difference in net income between April and May is
Now, to calculate the percent increase, you have to divide the change in net income by the original income in April:
But there’s a final trick in the question. The answer is not 1.5%. Remember, to get percents, you have to multiply by 100. The answer is $1.5 × 100 = 150%. The SAT will certainly include 1.5% as one of its answer choices to try to fool you.
Double Table Questions
The new SAT puts special emphasis on questions that ask you to relate the data contained in two different tables.
If Tiny Tim only eats vanilla ice cream and King Kong only eats chocolate, how much do the two of them spend on ice cream in a year?
You need to be able to see the relationship between the data in the two tables and the question to figure out the answer. Here’s what the two tables tell you:
  1. How much one-scoop, two-scoop, and three-scoop cones cost for both vanilla and chocolate.
  2. How many one-, two-, and three-scoop cones Tiny Tim and King Kong ate in a year.
Since the question tells you that Tiny Tim only eats vanilla and King Kong only eats chocolate, you know that Tiny Tim eats 5 one-scoop vanilla cones ($1.00), 12 two-scoop vanilla cones ($1.50), and 8 three-scoop vanilla cones ($1.75). So, in one year, Tiny Tim spent
(5 × 1) + (12 × 1.5) + (8 × 1.75) = 5 + 18 + 14 =37
dollars on ice cream. King Kong, meanwhile, spent
(16 × 1.25) + (10 × 1.75) + (6 × 2) = 20 + 17.5 + 12 = 49.5
dollars. So, together, these two pigged out on $86.50 of ice cream.
Scatterplots
The new SAT may also give you a special kind of graph called a scatterplot. A scatterplot lives up to its name. It’s a graph with a whole lot of points scattered around:
But the thing about a scatterplot is that the plots aren’t scattered randomly. They have some sort of trend. And if you see the trend, you can draw a line that makes an average of the all the plots scattered around. Here’s a line for the previous example:
On the SAT, you won’t have to do more than identify which line is the right one for a particular scatterplot and perhaps tell whether the slope of that line is negative or positive. You already know how to tell positive and negative slope, so these should be a breeze.
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