Page 331 - Start Up Mathematics_8 (Non CCE)

Example 2: Draw a histogram for the following frequency table and answer the questions that follow:
(NCERT)
Weekly 800–810 810–820 820–830 830–840 840–850 850–860 860–870 870–880 880–890 890–900
wages
Number of 3 2 1 9 5 1 3 1 1 4
workers
(a) Which group has the maximum number of workers?
(b) How many workers earn ` 850 and
more? Y
(c) How many workers earn less than
` 850? 10
9
Solution: Since the first interval starts with 800, we 8
put a kink ( ) before the class interval 7
800–810 showing that the full distance 6
0 to 800 is not shown. 5
(a) Maximum number of workers are Number of workers 4
in the group 830–840. 3
(b) Number of workers who earn 2
more than ` 850 is: 1
1 + 3 + 1 + 1 + 4 = 10 0 800 810 820 830 840 850 860 870 880 890 900 X
(c) Number of workers who earn less Weekly wages
than ` 850 is:
3 + 2 + 1 + 9 + 5 = 20

Example 3: Study the given histogram and answer Y
the questions that follow. 7
(a) What information is depicted in the 6
histogram? 5
(b) What is the number of teachers in Number of teachers 4
the oldest age group in the school? 3
(c) What is the number of teachers 2
1
in the youngest age group in the
school? 0 20 25 30 35 40 45 50 55 X
(d) What is the class size of each class Ages (in years)
interval?
(e) What are the class marks of the first two class intervals?
(f) How many teachers are below 30 years of age?
Solution: (a) The histogram depicts ages of 26 teachers in a school.
(b) There are 3 teachers in the oldest age group, i.e., 50–55 years.
(c) There are 2 teachers in the youngest age group, i.e., 20–25 years.
(d) The class size of each interval is 5.
20 25+ 45
(e) Class marks of 20–25 = = = 22.5
2 2
25 30+ 55
Class marks of 25–30 = = = 27.5
2 2
(f) The number of teachers below 30 years is 6 (2 + 4).

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