The following table gives the monthly income of 10 employees in an office.
Income (in Rs): 1780, 1760, 1690, 1750, 1840, 1920, 1100, 1810, 1050, 1950. Calculate the A.M.

3

(a)

From the following data of the marks obtained by 60 students of a class.

Marks	20	30	40	50	60	70
No of students	8	12	20	10	6	4

3

(a)

From the following data of the marks obtained by 60 students of a class. Find mean using step deviation method​​​​​​​​​​​​​​​​​​​​​

Weight(in Kgs)	20	30	40	50	60	70
Number of students	8	12	20	10	6	4

3

(a)

Find the average of the following data:

Marks	0-10	10-20	20-30	30-40	40-50	50-60
No of students	8	12	20	10	6	4

3

(a)

Calculate Mean from the data given below using step deviation method:​​​​​​​

Marks	0-10	10-20	20-30	30-40	40-50	50-60
No of students	8	12	20	10	6	4

3

(a)

If the average of the following data is 20.2, find the value of M:

x	10	15	20	25	30
f	6	8	M	10	6

3

(a)

Find Mean from the data given below:

Mid Value	3	9	15	21	27	33	30
Frequency	14	12	21	22	15	10	6

3

(a)

What are the objectives of a statistical average?

3

(a)

What is weighted mean? When is it useful?

3

(a)

Give three mathematical properties of Arithmetic Mean.

3

(a)

What are the requisites of an ideal average?

3

(a)

"Averages are indicators of a series". How?

3

(a)

Mention merits and demerits of Mean. And list out any three examples of 'scope of averages in your classroom.

3

(a)

When is Arithmetic mean and weighted mean equal?

3

(a)

From the following data of the marks obtained by 60 students of a class mean was found to be 41 Show that \(\sum _{ i=1 }^{ n }{ F({ x }_{ i }-\overline { x } ) } =0\)

Marks	20	30	40	50	60	70
No of students	8	12	20	10	6	4

3

(a)

Find out combined mean from the following data.

	Group A	Group B	Group C
Mean	12	20	10
Number of items	20	30	40

3

(a)

There are 80 students in a class whose average marks in Statistics are 65. There are two sections in the class. In one section there are fifty students whose average marks are 62. Find the average marks of other section.

3

(a)

In a class average marks of boys and girls are 65 and 75 respectively. The combined average of all students taken together is 72. Find percentage of boys and girls in the class.

3

(a)

Average marks of 50 students were 42. Later it was decided to give a grace of 2 marks to al students. Marks of all students were adjusted accordingly. Find new mean.

3

(a)

A students scored 36, 40, 42, 45 and 25 marks in Hindi, English, Mathematics, Social science and Science respectively. It was decided to give double weightage to the marks of Hindi and English and triple weightage to the marks of Science. Find weighted as well as simple mean.

3

(a)