To calculate the mean deviation from the given data, let’s break down the key components shown in your notes:

Step-by-Step Breakdown:

1. Quantity Demanded (x) and Frequency (f):

   • We have a set of quantities demanded ($x$) ranging from 10 to 100 and their respective frequencies ($f$).

2. Calculate the Arithmetic Mean ($\bar{X}$):

   • The formula used here is: $\bar{X} = \frac{\sum fx}{\sum f}$
   • According to the table: $\sum fx = 9000 \quad \text{and} \quad \sum f = 150$
   • So, the arithmetic mean ($\bar{X}$) is: $\bar{X} = \frac{9000}{150} = 60$

3. Calculate Deviations ($|x - \bar{X}|$):

   • For each quantity demanded $x$, find the deviation from the mean: $|x - \bar{X}|$
   • The deviations are shown in the column with $|x - \bar{X}|$.

4. Multiply Deviations by Frequency ($f |x - \bar{X}|$):

   • Each deviation is multiplied by its corresponding frequency, shown as $f |x - \bar{X}|$.
   • The sum of these values, $\sum f |x - \bar{X}|$, is given as 3220.

5. Calculate Mean Deviation:

   • The mean deviation formula is: $\text{Mean Deviation} = \frac{\sum f |x - \bar{X}|}{\sum f}$
   • Substituting the values: $\text{Mean Deviation} = \frac{3220}{150} = 21.46$

Final Answer:

The mean deviation is approximately 21.46.

Would you like further details or clarification on any specific part of this calculation?

Related Questions:

1. How does mean deviation differ from standard deviation?
2. Why do we ignore the sign when calculating deviations?
3. How is mean deviation useful in data analysis?
4. What is the impact of outliers on mean deviation?
5. How would the calculations change if data were grouped?

Tip:

For a clearer understanding of data dispersion, try calculating both the mean deviation and standard deviation for comparison.