In Stuart Crainer's new book, The 75 Greatest Management Decisions Ever Made . . . and 21 of the Worst, he highlights such efforts as Apple's decision to chase the prize of the first salable PC, while pointing out such errors as Sony's decision not to license its Betamax videotapes. This book, which will be published in October, features many well-known management stories --Jeff Bezos' creation of Amazon.com, for example -- as well as several not so well known. How many people know that the first ad was said to have been placed in Thebes in 100 BC? It happened when someone lost a slave named Shem and offered a gold coin in exchange for his return. Published by the American Management Assn., New York, the book is organized under 10 headings, a few of which include: Industry Inventors; Marketing Magic; Lucky Foresight; and People Power.