NCERT Solutions for Class 7 maths chapter 3

Data Handlings

NCERT Solutions for Class 7 maths chapter 3 Exercise 3.2

Question 1

The scores in mathematics test (out of 25) of 15 students is as follows:

19, 25, 23, 20, 9, 20, 15, 10, 5, 16, 25, 20, 24, 12, 20

Find the mode and median of this data. Are they same?

Answer

Arranging in an ascending order

5, 9, 10, 12, 15, 16, 19, 20, 20, 20, 20, 23, 24, 25, 25

Mode,

Mode is the value which occurs most frequently.

So, mode is 20

Median,

Here n = 15, which is odd.

Where, n is the number of the students.

Median =
=
= = 8

Then, value on 8^th position is = 20

So the median is 20.

Yes, both the values are same.

Question 2

The runs scored in a cricket match by 11 players is as follows:

6, 15, 120, 50, 100, 80, 10, 15, 8, 10, 15

Find the mean, mode and median of this data. Are the three same?

Answer

Arranging in an ascending order

6, 8, 10, 10, 15, 15, 15, 50, 80, 100, 120

Mean,

Mean =
=
= = 39

Mode,

Mode is the value which occurs most frequently.

So, mode is 15

Median,

Here n = 11, which is odd.

Where, n is the number of players.

∴median =

= 6

Then, value of 6^th term = 15

So the median is 15.

No, the value of these three are not same.

Question 3

The weights (in kg.) of 15 students of a class are:

38, 42, 35, 37, 45, 50, 32, 43, 43, 40, 36, 38, 43, 38, 47

(i) Find the mode and median of this data.

(ii) Is there more than one mode?

Answer

Arranging in an ascending order, we get

32, 35, 36, 37, 38, 38, 38, 40, 42, 43, 43, 43, 45, 47, 50

(i)

Mode,

Mode is the value which occurs most frequently.

38 and 43 both occurs 3 times.

So, mode are 38 and 43.

Median,

Here n = 15, which is odd.

Where, n is the number of the students.

median =
=
= = 8

Then, value of 8^th term = 40

So the median is 40.

(ii) Yes, there are 2 modes for the given weights of the students.

Question 4

Find the mode and median of the data: 13, 16, 12, 14, 19, 12, 14, 13, 14

Answer

Arranging data in an ascending order, we get

= 12, 12, 13, 13, 14, 14, 14, 16, 19

Mode,

<

14 occurs most of times.

So, mode is 14.

Median

Here n = 9, which is odd.

Where, n is the number of the students.

∴median =

== 5

Then, value of 5^th term = 14

Hence, the median is 14.

Question 5

Tell whether the statement is true or false:

(i) The mode is always one of the numbers in a data.

(ii) The mean is one of the numbers in a data.

(iii) The median is always one of the numbers in a data.

(iv) The data 6, 4, 3, 8, 9, 12, 13, 9 has mean 9.

Answer

(i)True.

(ii)False.

(iii)True.

(iv)False.