Strategy #18 Know your way around Graphs, Charts and Tables
• Use the information in charts and tables effectively.
• Pay close attention to scale and read carefully. Don’t assume that the horizontal and vertical axes have the same scale.
• Read how the axes are labeled. When you need to interpret the slope, putting the vertical units over the horizontal units will usually make this easy.
• Two-way tables usually require you to fill parts of them in. Often totals are left out, and you’ll need to compute these. Only take the time to fill in the parts you need if you can determine this.
Example 1 (practice test 6)
Calculator ok
We are given that this is a linear function. From the table we see that for a positive change of two units in x, we have a positive change of 6 units in y. Therefore an x change by +1 gives a y change by +3. From x=2 to x=3 is an x change of +1, so the corresponding y-value will be 4+3=7. Choice B is correct.
Example 2 (practice test 6)
Calculator ok
This is a two-way table. The problem is only interested in vanilla, so we only look at the Vanilla column. Since we want the fraction of those who chose hot fudge topping, we need the total who chose vanilla: 8+5=13. So the fraction is just: 8/13. Choice D is correct.