Question

if there are two groups containing 30 and 20 observations and having 50 and 60 as arithmetic means, the combined arithmetic mean is.
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Answer 1

explanation step by step...

sum of observation in 1st group=50×30=1500 & sum of observation in 2nd group=20×60=1200

total no. of observation=30+20=50

so, combined arithmetic mean= 1500+1200 divided by 50

=2700/50

=54

so, combined arithmetic mean of observation is 54.

answer