The mean of the following frequency table is 50. But the frequencies and in classes and are missing. Find the missing frequencies.
Class | ||||||
Frequency |
Step 1: The formula used to solve this problem:
Arithmetic Mean
where,
total number of frequencies
class size(units between each of the class interval)
Assumed mean(Total mid value of the class interval)
Sum of the frequency
Step 2: Make the required frequency distribution table:
First, we have to prepare a table to find the value of mid values and .
Class | Frequency | Mid values | ||
|
|
|
From the above table we get the values of,
Step 3: Find the missing frequencies
The given value of mean.
We will get, Arithmetic Mean
While solving equation (1) and (2), we get
Substitute in equation (2)
Therefore, and
Final Answer:
Hence , the missing frequencies are and