Mean of Ungrouped Data

Q.

The marks obtained by the students of a class , in a exam which was out of 50 mark given below

$\begin{array}{cc}\text{Marks}& \text{Number of students}\\ 5& 1\\ 7& 2\\ 11& 2\\ 16& 3\\ 21& 5\\ 24& 6\\ 28& 3\\ 32& 5\\ 34& 8\\ 39& 6\\ 43& 4\\ 45& 2\\ 49& 3\end{array}$

(i) Find the mean for the ungrouped data.

(ii) Represent the same data as grouped data, with class interval of width = 10 [4 MARKS]

Q.

The mean of the following distribution is ____.
$$\begin{array}{ccccc}{x}_i& \text{10}& \text{13}& \text{16}& \text{19}\\ f_i& \text{2}& \text{5}& \text{7}& \text{6}\end{array}$$

1. 15.2

2. 15.35

3. 15.55

4. 16

Q. The children in a class did a survey of the number of siblings (brothers and sisters) each of them had. The results are recorded in the following table. Calculate the mean number of siblings.

1. 2.6
2. 2.5
3. 3
4. 2

Q.

If the mean of the following data is 20 then the value of p is ___

$$\begin{array}{cccccc}{x}_i& \text{10}& \text{p}& \text{18}& \text{21}& \text{25}\\ f_i& \text{10}& \text{15}& \text{7}& \text{9}& \text{9}\end{array}$$

1. 24

2. 13

3. 11

4. 12

Q.

If the mean of the following data is 17 then the value of p is ___ .

$$\begin{array}{cccccc}{x}_i& \text{10}& \text{p}& \text{18}& \text{21}& \text{25}\\ f_i& \text{10}& \text{15}& \text{7}& \text{9}& \text{9}\end{array}$$

Q.

The marks obtained by 40 students in mathematics (out of 100) is presented in the table below. Find the mean using direct method.

$$\begin{array}{cccccc}ClassInterval& 0-10& 10-20& 20-30& 30-40& 40-50\\ Numberofstudents& 3& 4& 13& 15& 5\end{array}$$

1. 28.75

2. 25.2

3. 26.4

4. 29.9

Q.

250 students of class X of a school appeared in a test of 100 marks and the data about the marks secured is as below.

$$\begin{array}{cccccc}MarksSecured& 0-20& 20-40& 40-60& 60-80& 80-100\\ Numberofstudents& 20& 35& 65& 60& 70\end{array}$$

Q.

If the mean of the following data is 17, then the value of 'p' is ___

$\begin{array}{cccccc}{x}_i& \text{10}& \text{p}& \text{18}& \text{21}& \text{25}\\ f_i& \text{10}& \text{15}& \text{7}& \text{9}& \text{9}\end{array}$

1. 15

2. 24

3. 16

4. 14

Q.

The marks obtained by 40 students in mathematics (out of 100) is presented in the table below. Find the mean.

$$\begin{array}{cccccc}ClassInterval& 0-10& 10-20& 20-30& 30-40& 40-50\\ Numberofstudents& 3& 4& 13& 15& 5\end{array}$$

1. 28.75

2. 25.2

3. 26.4

4. 29.9

Q.

The formula for finding mean by direct method is $\frac{\sum (A\times B)}{\sum A}$

Where B and A are respectively:

1. class mark, frequency of the class

2. Class size, average frequency

3. Frequency of the class, class mark

4. Average frequency, class size

Q.

$\sum$fx = 5x + 2, $\sum$f = 12. If the mean of the distribution is 6, what is the value of x?

1. 14

2. 15

3. 18

4. 12

Q.

$\sum fx=5x+2$, $\sum f=12$. If the mean of the distribution is 6, what is the value of x?

1. 18

2. 12

3. 15

4. 14

Q.

Find the frequency of 40 in the following given set of data.

10, 40, 80, 100, 60, 40, 30, 40, 20, 40.

1. 3

2. 1

3. 2

4. 4

Q.

If the mean of the following data is 17 then the value of p is

___

$$\begin{array}{cccccc}{x}_i& \text{10}& \text{p}& \text{18}& \text{21}& \text{25}\\ f_i& \text{10}& \text{15}& \text{7}& \text{9}& \text{9}\end{array}$$

Q.

A person recorded the speed (in km/hr) of 10 motorists as 48, 52, 57, 55, 45, 39, 61, 49, 51 and 43. The average speed of the motorists is

1. 55 km/hr

2. 54 km/hr

3. 50 km/hr

4. 57 km/hr

Q.

If the mean of the following data is 17 then the value of p is ___

$$\begin{array}{cccccc}{x}_i& \text{10}& \text{p}& \text{18}& \text{21}& \text{25}\\ f_i& \text{10}& \text{15}& \text{7}& \text{9}& \text{9}\end{array}$$

Q. There are four children A, B, C and D. A has 6 chocolates, B has 7 chocolates, C has 8 chocolates and D has 10 chocolates. Which of these children nearly has the average number of chocolates?

1. A
2. B
3. C
4. D

Q.

The formula for finding mean by direct method is
$\frac{\sum (A\times B)}{\sum A}$

where B and A are respectively are _______.

1. frequency of the class, class mark
2. class size, average frequency
3. average frequency, class size
4. class mark, frequency of the class

Q. What is the mean of the given data?

$\begin{array}{cc}x& f\\ 4& 10\\ 8& 11\\ 12& 9\\ 16& 13\end{array}$

1. 10
2. 10.33
3. 43
4. 444

Q.

The formula for finding mean by direct method is
$\frac{\sum (A\times B)}{\sum A}$

where B and A are respectively are _______.

1. class mark, frequency of the class
2. frequency of the class, class mark
3. class size, average frequency
4. average frequency, class size

Q. $\begin{array}{cc}{x}_i& f_i\\ 4& 10\\ 8& 11\\ 12& 9\\ 16& 13\end{array}$
Find $\sum f_i{x}_i$ from the given table.

1. 444
2. 208
3. Data inadequate
4. 434

Q.

Obtain the mean of the following distribution.

Frequency	Variable
$4$	$4$
$8$	$6$
$14$	$8$
$11$	$10$
$3$	$12$

Q.

The marks obtained by the students of a class, in an exam which was out of 50 marks is given below :

$\begin{array}{cc}Marks& Numberofstudents\\ 5& 1\\ 7& 2\\ 11& 2\\ 16& 3\\ 21& 5\\ 24& 6\\ 28& 3\\ 32& 5\\ 34& 8\\ 39& 6\\ 43& 4\\ 45& 2\\ 49& 3\end{array}$

Find the mean for the ungrouped data.

1. 29.94

2. 24

3. 28

4. 30.5

Q.

Find the mean.

$$\begin{array}{cccccc}{x}_i& 10& 14& 18& 21& 25\\ f_i& 10& 15& 7& 9& 9\end{array}$$

Q.

The formula for finding mean by direct method is
$\frac{\sum (A\times B)}{\sum A}$

where B and A are respectively are _______.

1. class size, average frequency
2. class mark, frequency of the class
3. average frequency, class size
4. frequency of the class, class mark

Q.

The mean of the following distribution is
$$\begin{array}{ccccc}{x}_i& \text{10}& \text{13}& \text{16}& \text{19}\\ f_i& \text{2}& \text{5}& \text{7}& \text{6}\end{array}$$

1. 15.35

2. 15.55

3. 16

4. 15.2

Q.

A person recorded the speed (in km/hr) of 10 motorists as 48, 52, 57, 55, 45, 39, 61, 49, 51 and 43. The average speed of the motorists is

1. 57 km/hr

2. 50 km/hr

3. 55 km/hr

4. 54 km/hr

Q.

$\sum g_x$ = 8y + 18, $\sum g$ = 10. If the mean of the distribution is $5$ , what is the value of $y$?

1. 12

2. 14

3. 15

4. 18

Q. A student got marks in $5$ subjects in a monthly test is given below
$2,3,4,5,6$
in these obtained marks, $4$ is the

1. Mean and median
2. Mean but no median
3. Median but no mean
4. Mode

Q.

The mean of the following distriution is
$$\begin{array}{ccccc}{x}_i& \text{10}& \text{13}& \text{16}& \text{19}\\ f_i& \text{2}& \text{5}& \text{7}& \text{6}\end{array}$$

1. 15.2

2. 15.35

3. 15.55

4. 16