Question

the mean of 35 observation is 20 ,out of which mean of first 18 observation is 15 and mean of last 18 observation is 25 find the 18th observation ?


it's urgent​

Answer 1

Let x is the total sum of observations.

then x/35=20

x=700

and let sum of 1st 18th observation be a and sum of last 18th observation be b.

then a=270 and b =450

as 18th observation is taken twice.

18th obs= a+b-x

=20.

mark on brain list