Question

please solve ....

question regarding ,

STATISTICS .....​

Answer 1

Weekly income        Number of families    

200 - 300                          4

300 - 400                          61

400 - 500                         118

500 - 600                         139

600 - 700                          126

700 - 800                          150

800 - 900                           2

Total frequency = 4 + 61 + 118 + 139 + 126 + 150 + 2

⇒ Total frequency = 600 .

Assumed mean (a) = 550 .

Class mark       di = a - yi   fi       fidi

250                  - 300           4     - 1200

350                  - 200           61    - 13200

450                  - 100            118   - 11800

550                       0             139      0

650                     100           126      12600

750                      200          150     30000

850                     300             2       600

Total fidi =  - 1200 - 13200 - 11800 + 0 + 12600 + 30000 + 600

⇒ fidi = 17000

Mean = a + total fidi / total fi

⇒ 550 + 17000/600

⇒ 550 + 28.33

⇒ 578.33

∴ The mean is 578.33 .

Explanation :-

→ The assumed mean is the middlemost term .

→ The class mark is the average between the class intervals.

→ The sum of frequencies is calculated and the sum of the products of frequency and the deviation is added.

→ Then we divide the result and get the required mean .