Question

CLASS 9
DIRECT MEAN METHOD
FULL EXPLANATION ANSWER

Answer 1

Direct Method -

We will be finding the mean by using direct method since it would be easy as compared to others.

In direct method, we find the class marks of class interval. The class marks would be represented by x. Class marks can be calculated using the following formula i.e.,

$\qquad \frak{Class \: marks = \frac{(lower \: \: limit+upper \: \: limit) }{2} }$

To find the mean, use the formula,

$\: \qquad \sf \: mean = \frac{ \sum f_ix_i}{ \sum f _i}$

Frequency distribute table

Please see the attachment pic

Since, mean

$\: \qquad \sf \implies \frac{ \sum f_ix_i}{ \sum f _i}$

$\qquad \qquad \implies \cancel \frac{162}{20}$

$\qquad \qquad \implies \frac{81}{10}$

$\qquad \qquad \implies \frak{8.1}$

The mean number of plants per house is 8.1.