Question

The following table gives the literacy rate (in percentage) of 35 cities. Find the mean literacy rate.

Literacy rate (in %)	45 − 55	55 − 65	65 − 75	75 − 85	85 − 95
Number of cities	3	10	11	8	3

Answer 1

To find the class marks, the following relation is used.

Class size (h) for this data = 10

Taking 70 as assumed mean (a), d_i, u_i, and f_iu_i are calculated as follows.

Literacy rate (in %)	Number of cities fi	xi	di = xi − 70		fiui
45 − 55	3	50	− 20	− 2	− 6
55 − 65	10	60	− 10	− 1	− 10
65 − 75	11	70	0	0	0
75 − 85	8	80	10	1	8
85 − 95	3	90	20	2	6
Total	35				− 2

From the table, we obtain

Therefore, mean literacy rate is 69.43%.