Group of 8 numbers-Rejoinder

Only one member-Shekar- could send an answer which was correct
The answer is that the 8th number is 25
This is arrived at as follows-
The average of the first 2 being 15.5 their total is 31.
The average of the next 3 being 64/3 their total is 64.
The average of all the 8 numbers being 20,their total is 160.
Thus the total of the last 3 should be 160-31-64=65
If the 6th number is denoted by 'x' the 7th and 8th numbers will be (x+4) and (x+7)
So their total will be x+(x+4)+(x+7)=3x+11.
Equating this to 65 we find x,the 6th number is (65-11)/3=18
Hence the 7th and 8th numbers are 22 and 25  

Bookworm's travel

Here is a puzzle-
A bookworm eats from the first page of an encyclopedia to the last page.The bookworm eats in a straight line.The encyclopedia consists of ten 1000 page volumes and is sitting on a bookshelf in the usual order Not counting covers,title pages etc how many pages does the bookworm eat through?
Dont say it is easy- it eats through 10000 pages.
It actually eats through 8000 pages.Remember when the encyclopedia is in the correct order on the shelf,the first volume is on the left.so the first page is not on the extreme left.So also the last page is not at the extreme right.Thus only the middle 8 volumes consisting of 8000 pages has been travelled through..