# Construct a Frequency Polygon for the Following Data: - Mathematics

Graph
Sum

Construct a frequency polygon for the following data:

 Class-Intervals 10 - 14 15 - 19 20 - 24 25 - 29 30 - 34 Frequency 5 8 12 9 4

#### Solution

The class intervals are inclusive. We will first convert them into the exclusive form.

 Class-Interval Frequency 9.5 - 14.5 5 14.5 - 19.5 8 19.5 - 24.5 12 24.5 - 29.5 9 29.5 - 34.5 4

Steps:

1. Draw a histogram for the given data.
2. Mark the mid-point at the top of each rectangle of the histogram drawn.
3. Also, mark the mid-point of the immediately lower class-interval and mid-point of the immediately higher class-interval.
4. Join the consecutive mid-points marked by straight lines to obtain the required frequency polygon.

The required frequency polygon is as follows:

Concept: Graphical Representation of Data
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#### APPEARS IN

Selina Concise Mathematics Class 9 ICSE
Chapter 18 Statistics
Exercise 18 (B) | Q 3 | Page 233