Question

the mean score of 25 observations is 80 and the mean of another 55 observations is 80 . Determine the mean score of the whole set of observations​

Answer 1

Here is your solution.

Hope it helps you!

Answer 2

mean of first 25 is 80

hence , sum of them is 25×80

=2000

mean of next 55 is 80

hence , sum of them is 55×80

=4400

there are total 25+55 obs.

=80 obs.

sum of 25 + sum of 55

---------------------------------------

80

2000+ 4400

----------------------

80

6400

-----------

80

80 is the answer

hope you get it