A nationwide telecommunications company, "ConnectNet," wants to evaluate customer satisfaction with its new mobile app. The company has a customer base of 500,000 users across the country. To gather feedback, the company randomly selects 50 customers and sends them a survey asking them to rate their satisfaction with the app on a scale from 1 to 10 Of the 50 customers, 40 responded, and the average satisfaction score was 8.7 Based on this, the company concludes that the new mobile app is well-received by its customer base. What is the primary issue with this study?