**NCERT Solutions for Class 9 Maths Chapter 14
Statistics Ex 14.2**

NCERT Solutions for Class 9 Maths Chapter 14 Statistics Ex 14.2
are the part of NCERT Solutions for Class 9 Maths.
Here you can find the NCERT Solutions for Chapter 14 Statistics Ex 14.2.

**Ex 14.2 Class 9 Maths Question 1.****
**The blood groups of 30 students of
class VIII are recorded as follows:

A, B, O, O, AB, O, A, O, B, A, O, B, A, O, O,

A, AB, O, A, A, O, O, AB, B, A, O, B, A, B, O

Represent this data in the form of a frequency distribution table. Which is the most common and which is the rarest blood group among these students?

**Solution:****
**The required frequency distribution
table is as follows:

**Ex 14.2 Class 9 Maths Question 2.****
**The distance (in km) of 40
engineers from their residence to their place of work were found as follows:

5 3
10 20 25
11 13 7
12 31

19 10
12 17 18
11 32 17
16 2

7 9
7 8 3
5 12 15
18 3

12 14
2 9 6
15 15
7 6 12

Construct a grouped frequency distribution table
with class size 5 for the data given above taking the first interval as 0 – 5
(5 not included). What main features do you observe from this tabular
representation?

**Solution:****
**Here, the observation with minimum
and maximum values are 2 and 32, respectively.

∴ The class intervals are as follows:

0 – 5, 5 – 10, 10 – 15, 15 – 20, 20 – 25, 25 – 30, 30 – 35

The required frequency distribution table is as follows:

From the above table we observe that:

(i) Frequencies of class intervals 5 – 10 and 10 – 15 are equal, i.e., 11 each.
It shows that the maximum number of engineers have their residences at 5 to 15
km away from their work place.

(ii) Frequencies of class intervals 20 – 25 and 25 – 30 are also equal, i.e., 1
each. It shows that the minimum number of engineers have their residences at 20
to 30 km away from their work place.

**Ex 14.2 Class 9 Maths Question 3.****
**The relative humidity (in %) of a
certain city for a month of 30 days was as follows:

(ii) Which month or season do you think this data is about?

(iii) What is the range of this data?

**Solution:****
**Here, the lowest value of observation
= 84.9

The highest value of observation = 99.2

So, class intervals are 84 – 86, 86 – 88, 88 – 90, ……., 98 – 100

(i)
Thus, the required frequency distribution table is as follows:

(iii) Range = (Highest observation) – (Lowest observation) = 99.2 – 84.9 = 14.3

**Ex 14.2 Class 9 Maths Question 4.****
**The heights of 50 students,
measured to the nearest centimetres have been found to be as follows:

(ii) What can you conclude about their heights form the table?

**Solution:****
**(i) Here, the lowest value of the
observation = 150

The highest value of the observation = 173

So, the class intervals are 150 – 155, 155 -160, …, 170 – 175.

The required frequency distribution table is as follows:

(ii)
From the above table, we can conclude that more than 50% of the students are
shorter than 165 cm.

**Ex 14.2 Class 9 Maths Question 5.****
**A study was conducted to find out
the concentration of sulphur dioxide in the air in parts per million (ppm) of a
certain city. The data obtained for 30 days is as follows:

(ii) For how many day’s was the concentration of sulphur dioxide more than 0.11 parts per million?

**Solution:****
**(i) Here, the lowest value of the
observation = 0.01

The highest value of the observation = 0.22

So, the class intervals are 0.00 – 0.04, 0.04 – 0.08, …., 0.20 – 0.24

The required frequency distribution table is as follows:

(ii)
The concentration of sulphur dioxide was more than 0.11 ppm for 8 days.

**Ex 14.2 Class 9 Maths Question 6.****
**Three coins were tossed 30 times
simultaneously. Each time the number of heads occurring was noted down as
follows:

0 1
2 2 1
2 3 1
3 0

1 3
1 1 2
2 0 1
2 1

3 0
0 1 1
2 3 2
2 0

Prepare a frequency distribution table for the
data given above.

**Solution:****
**The required frequency distribution
table is as follows:

**Ex 14.2 Class 9 Maths Question 7.****
**The value of Ï€ upto 50 decimal
places is given below

3.14159265358979323846264338327950288419716939937510

(i) Make a frequency distribution of the digits from 0 to 9 after the decimal point.

(ii) What are the most and the least frequently occurring digits?

**Solution:****
**(i) The required frequency
distribution table is as follows:

**Ex 14.2 Class 9 Maths Question 8.****
**Thirty children were asked about
the number of hours they watched TV programmes in the previous week.

The results were found as follows:

1 6
2 3 5
12 5 8
4 8

10 3
4 12 2
8 15 1
17 6

3 2
8 5 9
6 8 7
14 12

(i) Make a grouped frequency distribution table
for this data, taking class width 5 and one of the class intervals as 5 – 10.

(ii) How many children watched television for 15
or more hours a week?

**Solution:****
**(i) Here, the lowest value of the
observation = 1 and the highest value of the observation = 17

So, the class intervals are 0 – 5, 5 – 10, 15 – 20

The required frequency distribution table is as
follows:

**Ex 14.2 Class 9 Maths Question 9.****
**A company manufactures car
batteries of a particular type. The lives (in years) of 40 such batteries were
recorded as follows:

**Solution:****
**Here, the lowest value of the
observation = 2.2

and the highest value of the observation = 4.6

So, the class intervals are 2.0 – 2.5, 2.5 – 3.0, …., 4.5 – 5.0

The required frequency distribution table is as follows:

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