Calculate the mean deviation about mean and standard deviation for the following distribution.

Classes	Frequencies
20-40	3
40-80	6
80-100	20
100-120	12
120-140	9

6

(a)

The sum of 10 values is 100 and the sum of their squares is 1090. Find the coefficient of variation.

6

(a)

The yield of wheat and rice per acre for4 10 districts of a state is as under:

District	1	2	3	4	5	6	7	8	9	10
Wheat	12	10	15	19	21	16	18	9	25	10
Rice	22	29	12	23	18	15	12	34	18	12

Calculate for each crop
(i) Range
(ii) Q.D.
(iii) Mean deviation about mean
(iv) Mean deviation about median
(v) Standard deviation
(vi) Which crop has greater variation?
(vii) Compare the values of different measures for each crop.

6

(a)

A batsman is to be selected for a cricket team. The choice is between X and Y on the basis of their five previous scores which are:

X	25	85	40	80	120
Y	50	70	65	45	80

6

(a)

To check the quality of two brands of light bulbs, their life in burning hours was estimated as under for 100bulbs of each brand.

Life (in hrs.)	No. of bulbs Brand A	Brand B
0-50	15	2
50-100	20	8
100-150	18	60
150-200	25	25
200-250	22	5
	100	100

Which brand gives higher life?
Which brand is more dependable?

6

(a)