Question

151. (a) Find the mean of the following data :
18, 33, 30, 21 and 13.
Also, find the sum of deviations of this
data from the mean.
(b) If 150 is the mean of 200 observations
and 100 is the mean of some 300 other
observations, find the mean of the
combination.​

Answer 1

Step-by-step explanation:

a) (18+33+30+21+13)/5

115/5

23

b) 200 observations mean = 150

200 observations total= 150*200=30000

300 observations mean = 100

300 observations total= 100*300=30000

500 observations total= 30000+30000

= 60000

500 observations mean= 60000/500

=120

Answer 2

Answer:

(a). The mean of observation are = 13,18,21,30,33

mean = 13+18+21+30+33/5 = 115/5 = 23

Mean Ans = 23

The sum of deviations = (13-23)+(18-23)+(21-23)+(30-23)+(33-23)

= -10-5-2+7+10

deviations = 0 (Ans)

(b). Mean of 200 observations = 150

sum of 200 observation = 200×150 = 30,000

mean of 300 observation = 100

sum of 300 observation = 300×100 = 30,000

Total sum = 30,000+30,000 = 60,000

no.of observations = 300 + 200 = 500

mean = total sum / no of observation

= 60,000/500 = 120

Mean = 120 (Ans)