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

Explanation

To find the missing frequency \( f \) given that the mean pocket allowance is Rs 18, we can follow these steps:

### Step 1: Understand the Mean Formula
The mean of a frequency distribution is calculated using the formula:
\[ \text{Mean} = \frac{\sum (f_i \cdot x_i)}{\sum f_i} \]
where \( f_i \) is the frequency and \( x_i \) is the mid-value of the class intervals.
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