Arithmatic mean

Question

the arithmetic mean of 25 numbers is 36. if arithmetic mean of first 13 and last 13 numbers are 32 and 39 respectively, find the 13th number

Answer 1

######### yer numbers dont make sens

num numbers=25

AVERAEJ =36

sum=averaej*(num numbers)=25*36=900

yu sae first 13 numbers averaej=32,so sum av first 13=13*32=416

last 13=39, so sum=13*39= 507

sum av 2 grueps=416+507=923

##### last 13 duplikate the middel number...its in both grueps

middel numb=923=900=23

so middel number=900 -(