Frequency Polygons Flashcards

All 5 cards in this deck

What do you plot for each class when drawing a frequency polygon?

The midpoint of the class against its frequency.
e.g. class $130\text{–}140$ with frequency 4 gives the point $(135, 4)$

How do you find the midpoint of a class interval?
e.g. $150 \le h < 160$

Add the two end values and divide by 2.
$(150+160)\div 2 = 155$

How are the points of a frequency polygon joined?

With straight line segments, in order from left to right.

What type of data is a frequency polygon used for?

Grouped (usually continuous) numerical data.

True or false? A frequency polygon must be closed by joining the last point back to the first.

False.
The first and last points are not joined; the line simply stops at the end points.