Page 326 - Start Up Mathematics_8 (Non CCE)

Step 2: Now group these observations in the table given below:

Blood group Tally marks Number of students

A
B
AB

O
Total

Step 3: Draw a bar graph for the table in step 2 on the white sheet. Cut strips of different colours from
the coloured sheets and paste them on the bars.
Observations: (i) The most common blood group in the class is ___________________.
(ii) The least common blood group in the class is ___________________.

AT a Glance

1. The number of times an observation occurs in the given data is called the frequency of the
observation.
2. Range = Greatest value – Smallest value
3. Class size = Difference between two successive lower class limits or two successive upper class limits

Upperlimit +Lower limit
4. Class-mark =
2
Ê
5. If a – b is an inclusive class interval, then its exclusive class interval becomes a - hˆ - Ê Á b + hˆ ˜
Á
˜
where h = Lower limit of a class – Upper limit of previous class Ë ¯ 2 Ë ¯ 2
6. A bar graph is a pictorial representation of numerical data in the form of rectangles of equal width and
varying heights.

Review Exercises

Multiple ChoiCe Questions
1. The number of times on observation occurs in a data is called its:
(a) range (b) frequency (c) class size (d) none of them

2. The class marks of an interval are also known as the:
(a) width of class interval (b) class size
(c) mid-value of class interval (d) class limit
3. The range of the data 6, 12, 9, 15, 8, 5, 14, 7, 6, 3 is:
(a) 13 (b) 10 (c) 11 (d) 12
4. The inclusive class intervals are also called:
(a) discontinuous class intervals
(b) continuous class intervals
(c) unequal class intervals
(d) higher class intervals

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