NCERT solutions for class 9 Maths chapter 14 Statistics (Exercise 14.4)

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NCERT solutions for class 9 Maths


Statistics


Chapter 14


Exercise 14.4


Ex 14.4 Question 1.


The following number of goals were scored by a team in a series of 10 matches
2, 3, 4, 5, 0, 1, 3, 3, 4, 3.
Find the mean, median and mode of these scores.
Solution:
Number of observations (n) = 10

Mean = 2.8

Arranging the data in ascending order:
0,1, 2, 3, 3, 3, 3, 4, 4, 5
∵ number of observation = 10, an even number

Median = 3

Here,the observation 3 occurs maximum 4 times,
Hence,he mode of observation = 3.
Mode = 3


Ex 14.4  Question 2.


In a mathematics test given to 15 students, the following marks (out of 100) are recorded
41, 39, 48, 52, 46, 62, 54, 40, 96, 52, 98, 40, 42, 52, 60
Find the mean, median and mode of this data.
Solution:
Number of observations (n) = 15

Mean = 54.8

Arranging the data in ascending order,
39, 40, 40, 41, 42, 46, 48, 52, 52, 52, 54, 60, 62, 96,98
∵ Number of observation (n) = 15, an odd number

Median = 52

Here, the observation 52 occurs maximum 3 times,
Hence,he mode of observation = 52.
Mode = 52


Ex 14.4  Question 3.


The following observations have been arranged in ascending order. If the median of the data is 63, find the value of x.
29, 32, 48, 50, x, x + 2, 72, 78, 84, 95
Solution:
Number of observations (n) = 10 (an even number)

Median = 63 [Given]
∵ x + 1 = 63 ⇒ x = 63 – 1 = 62
Hence, the value of x = 62.


Ex 14.4 Question 4.


Find the mode of 14, 25,14, 28,18,17,18,14, 23, 22,14 and 18.
Solution:
Arranging the given data in ascending order,

14, 14, 14, 14, 17, 18, 18, 18, 22, 23 25, 28.
Here, the number 14 is occurs  maximum (4) times.

Hence, the mode of the observation = 14


Ex 14.4  Question 5.


Find the mean salary of 60 workers of a factory from the following table

Solution:


Ex 14.4 Question 6.


Give one example of a situation in which
(i) the mean is an appropriate measure of central tendency.
(ii) the mean is not an appropriate measure of central tendency but the median is an appropriate measure of central tendency.
Solution:
(i) Mean height of the family members of a family.
(ii) Median marks obtained by students (out of 100) in maths test.