Name: Finding Class Mark in Grouped Data
Uploaded: 2019-07-19
Duration: 4 min 48 s
Description: What is the mid-value or class mark of class 20-30? Bringing to you the answer to this question, this video will explain to you the method of finding the cla...

Question

Construct a frequency polygon for the following distribution:

Class intervals	$0 - 4$	$4 - 8$	$8 - 12$	$12 - 16$	$16 - 20$	$20 - 24$
Frequency	$4$	$7$	$10$	$15$	$11$	$6$

Accepted Answer

We are given to construct a frequency polygon for the following distribution:

Class intervals $0 - 4$ $4 - 8$ $8 - 12$ $12 - 16$ $16 - 20$ $20 - 24$

Frequency $4$ $7$ $10$ $15$ $11$ $6$

We know that when the mid-points of the adjacent class intervals, of the given frequency distribution, are joined by straight line segments, the figure so obtained is called a frequency polygon.

To complete the polygon, the mid-points at each end are joined to the immediately lower or higher mid-point at zero frequency, i.e. on the $x$ -axis.

A frequency polygon can be drawn (i) using a histogram (ii) without using a histogram.

Here, we shall draw the frequency polygon using a histogram.

Steps:

a) Using the given frequency distribution, draw a histogram.
b) Mark the mid-point of the upper horizontal line of each rectangle.

c) Mark the mid-point of the class interval, adjacent to the first-class interval, at zero frequency and also mark the mid-point of the class interval, adjacent to the last class interval, at zero frequency.
d) Join all the mid-points marked to get the required frequency polygon.

The frequency polygon is shown in the following figure

Class intervals	$10 - 20$	$20 - 30$	$30 - 40$	$40 - 50$	$50 - 60$
Frequency	$3$	$5$	$6$	$4$	$2$

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

Daily wages (in $₹$ )	$125 - 175$	$175 - 225$	$225 - 275$	$275 - 325$	$325 - 375$
Number of workers	$4$	$20$	$22$	$10$	$6$

R K Bansal Solutions for Exercise 1: EXERCISE

R K Bansal Mathematics Solutions for Exercise - R K Bansal Solutions for Exercise 1: EXERCISE

Questions from R K Bansal Solutions for Exercise 1: EXERCISE with Hints & Solutions

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