my_auto_approve_good_ratings.php

<?php
/**
 * Automatically approve ratings > 3 out 5 stars.
 */
function my_auto_approve_good_ratings( $auto_approve_ratings, $rating_entry ) {
		
	$rating_result = mrp_calculate_rating_entry_result( $rating_entry );
	
	if ( $rating_result['adjusted_star_result'] > 3 ) {
		return true;
	}
	
	return false;
}
add_filter( 'mrp_auto_approve_ratings', 'my_auto_approve_good_ratings', 10, 2 );