NCERT Solutions class 10 maths chapter 14
Statistics
NCERT Solutions class 10 maths chapter 14 Exercise 14.1
Question 1
A survey was conducted by a group of students as a part of their environment awareness
programme, in which they collected the following data regarding the number of plants in
20 houses in a locality. Find the mean number of plants per house.
Answer 1
We know the
Mean
=
162
/
20
= 8.1
We use this method because value of fi and Xi is very small
Question 2
Consider the following distribution of daily wages of 50 workers of a factory
Find the mean daily wages of the workers of the factory by using an appropriate method
Answer 2
Mean x̄ ==
150 + (20 ×
-12
/
50
)
= 150 – 4.8 = 145.20
The mean daily wage of the workers = 145.20
Question 3
The following distribution shows the daily pocket allowance of children of a locality.
The mean pocket allowance is Rs 18. Find the missing frequency f.
Answer 3
Mean =
=
(752+20f)
/
(752+20f)
)
Here mean= 18
⇒ 18 =
(752+20f)
/
(752+20f)
)
⇒ 18(44+f) = (752+20f)
⇒ 792+18f = 752+20f
⇒ 792+18f = 752+20f
⇒ 792 – 752 = 20f – 18f
⇒ 40 = 2f
⇒ f = 20
f = 20
Question 4
Thirty women were examined in a hospital by a doctor and the number of heart beats per
minute were recorded and summarised as follows. Find the mean heart beats per minute
for these women, choosing a suitable method.
Answer 4
Mean = x̄ =
A = 75.5 , h=3
= 75.5 + 3×(
4
/
30
)
= 75.5 +
4
/
30
= 75.5 + 0.4
= 75.9
Question 5
In a retail market, fruit vendors were selling mangoes kept in packing boxes. These
boxes contained varying number of mangoes. The following was the distribution of
mangoes according to the number of boxes.
Find the mean number of mangoes kept in a packing box. Which method of finding
the mean did you choose?
Answer 5
Mean = x̄ = A +h
∑fidi
/
∑fi
= 57 + 3(
75
/
400
)
= 57 + 0.1875
= 57.19
Question 6
The table below shows the daily expenditure on food of 25 households in a locality
Find the mean daily expenditure on food by a suitable method
Find the mean daily expenditure on food by a suitable method
Answer 6
Here a=225 , h=50
Mean =
= 225+50(
-7
/
25
)
= 225-14
= 211
Question 7
To find out the concentration of SO
2
in the air (in parts per million, i.e., ppm), the data
was collected for 30 localities in a certain city and is presented below:
Find the mean concentration of SO
2
in the air
Answer 7
Mean = x̄ =
=
2.96
/
30
= 0.099 ppm
Question 8
A class teacher has the following absentee record of 40 students of a class for the whole
term. Find the mean number of days a student was absent
Answer 9
Mean =
=
499
/
40
= 12.48
Question 9
The following table gives the literacy rate (in percentage) of 35 cities. Find the mean
literacy rate.
Answer 9
Mean =
here a=70 , h =10
= 70 + 10 x(
-2
/
35
)
= 69.42