In a retail environment, a company is analyzing customer interactions across various touchpoints, including in-store visits, website engagement, and social media interactions. They want to determine the overall effectiveness of their marketing strategy by calculating the Customer Interaction Score (CIS). The CIS is defined as the weighted average of interactions across these touchpoints, where in-store visits contribute 50%, website engagement contributes 30%, and social media interactions contribute 20%. If a customer has 10 in-store visits, 5 website engagements, and 2 social media interactions, how would you calculate the Customer Interaction Score for this customer?