Question

find the mean of 5 observation x,x+2,x+4,x+6,x+8 is 11.find the mean of 1st three observation

Answer 1

(x+x+2+x+4+x+6+x+8)÷5=11
(5x+20)÷5=11
5x+20=55
5x=35
X=7
First observation=x=7
Second observation=x+2=7+2=9
Third observation=x+4=7+4=11
I.e their ascending order is 7,9,11.
n=3
(n+1)÷2=(3+1)÷2
=4/2
=2 
I.e second observation
I.e median is 9

Answer 2

mean=x+x+2+x+4+x+6+x+8/5
mean=5x+20/5
11=5x+4
5x=11-4
5x=7
x=7/4
mean of 1st 3 observation=
mean=7/4+7/4+2+7/4+4
mean=(7+7+8+7+16)/4
mean=45/4
mean=11.25