Frequency Polygons Flashcards

All 6 cards in this deck

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

The midpoint of the class against its frequency.

How do you find the midpoint of a class interval?

e.g. $10 < s \leq 20$

Add the two class boundaries and halve: $\frac{10+20}{2} = 15$.

What are the steps to draw a frequency polygon from a grouped frequency table?

e.g. $0<s\leq 10$: $14$, $10<s\leq 20$: $18$

1. Find each class midpoint: $5$, $15$
2. Plot midpoint against frequency: $(5,14)$, $(15,18)$
3. Join consecutive points with straight line segments

How should the plotted points on a frequency polygon be joined?

With straight line segments, not a smooth curve.

True or false? The first and last points of a frequency polygon should be joined up to close the shape.

False. The line stops at the last plotted point; it is not closed.

What type of data is a frequency polygon suitable for?

Grouped data, usually continuous, given in class intervals.