To calculate the overall star rating and percentage breakdown by star, we do not 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 analyses reviews to verify trustworthiness.
I bought this set of cards for my son. Love it! It provides an easy way to help my son on practicing his reading skill. Very handy. We carry it around and practice even while waiting for restaurant seating.