Question

If the mean of a 10observation is 20and the another 15observation is 16 find the mean of all the 25 observation

Answer 1

sum of first 10 observations = mean * no. of observations = 10*20 = 200

similarly, sum of another 15 observations = 15*16 = 240

mean of all 25 observations = (200+240)/(10+15) = 17.6