Q30 of 37 Page 1

The following distribution shows the daily pocket allowance of children of a locality. The mean pocket allowance is Rs. 18. Find the missing frequency k.


We know the formula of mean is given by,


Mean =


Substituting mean = 18, ∑fixi = 704 + 20k & ∑fi = 40 + k in the above equation, we get


18 =


⇒ 18 (40 + k) = 704 + 20k


⇒ 720 + 18k = 704 + 20k


⇒ 20k – 18k = 720 – 704


⇒ 2k = 16


⇒ k = 16/2


⇒ k = 8


Thus, k = 8.


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