# The following distribution shows the daily pocket allowance given to the children of a multistory building. Class interval: 11 - 13

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The following distribution shows the daily pocket allowance given to the children of a multistory building. The average pocket allowance is Rs. 18.00. Find out the missing frequency.

 Class interval: 11 - 13 13 - 15 15 - 17 17 -19 19 - 21 21 - 23 23 - 25 Frequency: 7 6 9 13 .... 5 4

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Given,

Mean = 18

Let missing frequency be V

 Class interval Mid value (xi) fi fixi 11 - 13 12 7 84 13 - 15 14 6 84 15 - 17 16 9 144 19 - 21 20 V 20V 21 - 23 22 5 110 23 - 25 24 4 56 N = 44 + V $\sum$fixi = 752 + 20V

Mean = $\frac{\sum f_ix_i}{N}$

$18 = \frac{752+20V}{44+V}$

792 + 18V = 752 + 20V

792 – 752 = 20V – 18V

40 = 2V

V = 20