Question

The mean of 10 observations is 7 & the mean of 15 observations is12 then mean of all the observations

Answer 1

10 is the mean for 7 observations so the total for those 7 observations is = 10*7 = 70

Similarly, 5 is the mean for 3 observations so the total for those 3 observations is = 5*3 = 15

Thus total for (7+3) = 10 observations = 70+15 = 85

Mean = total/number of observations = 85/10 = 8.5


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Answer 2

10

Step-by-step explanation:

Given:

Mean of 10 observation (x) = 7

n = 10

$Mean = sum \ of \ observations / Number \ of \ Observation\\7 = sum \ of \ observations / 10\\70 = sum \ of \ observations$

∈x = 70

Given:

Mean of 15 observation (X) = 12

N = 15

$Mean = sum \ of \ observations / Number \ of \ Observation\\12 = sum \ of \ observations / 15\\180 = sum \ of \ observations$

∈X = 180

Total Sum = 180 + 70 = 250

Total number = 10 + 15 =25

$Mean = sum \ of \ observations / Number \ of \ Observation\\Mean = 250 / 25\\10 = Mean$

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