ACT Preparation / Unit 15 ACT 1406 worked example, 60 to 90 seconds
Reading a Display
The idea
A data display is read in three steps. First, read the title, the axis labels, the units, and the scale of each axis. Second, find exactly what the question asks for: a count, a percent, a difference, a median, a range. Third, read the needed values carefully, compute, and check that the answer fits the display's scale.
In practice
Worked example: a histogram of 40 students' commute times shows 6 in 0–9 minutes, 16 in 10–19, 10 in 20–29 and 8 in 30–39. What percent commute 20 minutes or more? 10 + 8 = 18 students, and 18/40 = 45%. Where is the median? It averages the 20th and 21st values, and since 6 + 16 = 22 values lie below 20 minutes, both fall in the 10–19 interval.
Where people slip
A histogram shows intervals, not exact values, so it can place the median in an interval but cannot give its exact value.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
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