To calculate the overall star rating and percentage breakdown by star, we don’t use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyzes reviews to verify trustworthiness.
Great material! However, I returned it after learning that I could rent an e-book (which is what I prefer) on Pearson's website for 9.99 a month. I didn't the book longer than a month so it worked out for me and is a lot cheaper.