Question:
The following table given the number of branches and number of plants in the garden of a school.
Solution:
Let the assume mean be $A=4$.
We know that mean, $\bar{X}=A+\frac{1}{N} \sum_{i=1}^{n} f_{i} d_{i}$
Now, we have $N=\sum f_{i}=200, \sum f_{i} d_{i}=-77$ and $A=4$
Putting the values in the above formula, we get
$\bar{X}=A+\frac{1}{N} \sum_{i=1}^{n} f_{i} d_{i}$
$=4+\frac{1}{200} \times(-77)$
$=4-0.385$
$=3.615$
$\approx 3.62$ ( approximate)
Hence, the mean number of branches per plant is approximately 3.62.