Using Suitable Diagram to Illustrate a Given Data

Students tend to confuse themselves the more when a question do not demands a particular diagram to be used to answer it. This tutorial will teach you how to choose a suitable diagram to be used for a particular data in a question.

When the question demands the determination or estimation of the MODE from the diagram we choose, we draw a HISTOGRAM. However, where the question demands the determination of the MEDIAN, QUARTILES, and PERCENTILES etc from the diagram we choose, we draw a CUMULATIVE FREQUENCY CURVE.

Let’s consider the following examples:

Example one:

The following is the table of the ages [to the nearest year] of the children at a birthday party.

Ages (years)	1	2	3	4	5	6	7	8	9	10
No. Of children	1	3	5	7	8	9	6	3	2	1

a.       Use a suitable diagram to illustrate the above data.

b.      From your diagram, find the modal age.

c.       Find the mean of the data.

d.      If a child is selected at random, what is the probability that he is older than the modal age?

Example two:

The table below represent the marks obtained by 40 students in an examination.

Marks	1-10	11-20	21-30	31-40	41-50	51-60	61-70	71-80	81-90	91-100
Frequency	1	4	5	7	7	6	4	3	2	1

a.       Illustrate the above data with a suitable diagram.

b.      From the diagram, find the inter-quartile range.

c.       Find the percentage of students who scored marks between 50 and 75.

d.      What is the probability of picking a script with the lower than 30%.

e.       Find the mark obtained by the student who was 6^th in the test.

NOTE:

The intention here is to show you the tips as to what suitable to choose to answer or illustrate a given diagram in a question, so the solutions to the above questions are not necessary.

Now from example one, the question demands the determination of the mode from the diagram we choose, so the appropriate diagram students must think of is HISTOGRAM.

On the other hand, the second example demands inter-quartile range and that the suitable diagram for the data is CUMULATIVE FREQUENCY CURVE.

 
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