Question

if the Mean of the observation x x +3 x +5 x +7 and x + 10 is 9 then find the mean of the last three observation

Answer 1

Mean =(x+x+3+x+5+x+7+x+10)/5

9*5=5x+25

45=5x+25

45-25=5x

20=5x

4=x

Last three number are, 9,11,14

Mean=(9+11+14)/3

Mean =34/3

Answer 2

Mean =(x+x+3+x+5+x+7+x+10)/5

9*5=5x+20.

45=5x+20

45-20=5x

25=5x

5=x

Last three number are, 10,12,15

Mean=(10+12+15)/3

Mean =37/3