Q. The following table gives the literacy rate (in percentage) of 35 cities.
Find the mean literacy rate.
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Literacy rate (in %) | 45 - 55 | 55 - 65 | 65 - 75 | 75 - 85 | 85 - 95 |
No. of cities | 3 | 10 | 11 | 8 | 3 |
Sol:
(Class interval)
Classmark
xi
frequency
( fi )
fixi
55 - 65
65 - 75
85 - 95
50
60
70
90
3
10
11
3
150
600
770
270
Total
--
Σ fi =
Σ fixi =
35
2430
Σ fixi
Σ fi
=
2430
35
=
69.43
Class width(h) =
10
75 - 85
80
8
640
What we need to find?
Literacy rate (in %)
No. of cities
Class width (h) is found by subtracting two consecutive lower limits or two consecutive upper limits
45 - 55
7
50 x 3
60 x 10
70 x 11
80 x 8
90 x 3
Adding all fi
Adding all fixi
By adding h to xi we get next xi
486
69.43
HOMEWORK
Exercise – 14.1 – Q.9