17
80
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Q. A student noted the number of cars passing through a spot on a road for
100 periods each of 3 minutes and summarised it in the table given below.
Find the mode of the data :
Sol:
Class width(h) =
10
Frequency
( fi )
10 - 20
20 - 30
30 - 40
40 - 50
Class
7
14
13
12
20
0 - 10
Maximum frequency is 20
50 - 60
11
The corresponding class 40 – 50 is modal class.
f1
f0
f2
∴
l
=
40,
h
=
10,
f1
=
20,
f0
=
12,
f2
11
=
Mode
=
l
+
2f1
×
h
– f0
– f2
f1
– f0
∴
Mode
=
40
+
2(20)
×
10
– 12
– 11
20
– 12
∴
Mode
=
40
+
Mode
=
40
+
4.7
∴
Mode
=
∴
44.7 cars
60 - 70
70 - 80
15
8
No. of cars | 0 - 10 | 10 - 20 | 20 - 30 | 30 - 40 | 40 - 50 | 50 - 60 | 60 - 70 | 70 - 80 |
Frequency | 7 | 14 | 13 | 12 | 20 | 11 | 15 | 8 |
No. of cars
Frequency
Find the mode of the data
Modal
Class
Class width (h) is found by subtracting two consecutive lower limits or two consecutive upper limits
For finding mode classes must be continuous
4.7
Frequency of the class
Preceeding the Modal class
Frequency of the class
succeeding the Modal class
What is the Maximum frequency?
Exercise 14.2 – Q.6