Note: RP; Reasonable Portion
My two cents:
Both clauses a and b specify the 10 percent rule. Clearly, 10 percent is a criterion, irrespective of whether the book contains chapters or not.
We shall also assume that the pages can be picked either in a serial or random fashion.
Scenario 1: If it is a 100 page book with no chapters at all(!).
RP: is simply 10% of the book - 10 pages, either in serial order or randomly.
Scenario 2: It is a 100 page book with chapters and all chapters are 10 pages each.
RP: is 10%, i.e., 10 random pages OR 1 chapter of 10 pages
Scenario 3: It is a 100 page book with three different size chapters - a)below 10, b)10, c)above 10
RP for, (in all cases conforming to the 10% quota, is only 10 pages):
3a: 1 chapter + [(10 - chapter size) pages]
3b: 1 chapter OR part of 1 chapter + [(10-chapter size) pages]
3c: 10 pages only of 1 chapter or 10 random pages from the book.
