Question

If di = xi - 20 , sigma fidi = 300
& sigma fi = 40
Fend the mean ?

PLEASE ANSWER IT CORRECT.​

Answer 1

Answer:

It is given that di = xi - 20 therefore A = 20

sigma fidi = 300

sigma fi = 40

therefore Mean = A + sigma fidi/sigma fi

Mean = 20 + 300/40

Mean = 20 + 7.5

Mean = 27.5

Answer 2

The mean = 27.5

Given :

$\sf \: d_i \: = \: x_i \: - \: 20$

$\sf \: \sum \: f_i \: d_i \: = \: 300$

$\sf \: \sum \: f_i = 40$

To find :

The mean

Formula Used :

$\sf Mean = a + \dfrac{\sum \:f_i \: d_i}{\sum \:f_i} \: \: where \: d_i = x_i - a$

Solution :

Step 1 of 2 :

$\sf \: d_i \: = \: x_i \: - \: 20$

Comparing with $\sf d_i \: = \: x_i \: - \: a$ we get a = 20

$\sf \: \sum \: f_i \: d_i \: = \: 300$

$\sf \: \sum \: f_i = 40$

Step 2 of 2 :

Calculate mean

$\sf Mean = a + \dfrac{\sum \:f_i \: d_i}{\sum \:f_i}$

$\sf \implies Mean = 20 + \dfrac{300}{40}$

$\sf \implies Mean = 20 +7.5$

$\sf \implies Mean = 27.5$

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