Amazon calculates a product's star ratings based on a machine learned model instead of a raw data average. The model takes into account factors including the age of a rating, whether the ratings are from verified purchasers and factors that establish reviewer trustworthiness.
Very good book I am very big fan of Mr. Narendra Kolhi and his writing skill. But I am very sad with amazon as they send me this book with very poor printing quality. Very bad font style is there in this book.