Jonas owns a pizza shop. He had 300 customers at the end of June, 310 customers at the beginning of June, and 20 new customers in June. What is his customer retention rate for June?

• A. 80%
• B. 90%
• C. 85%
• D. 95%

Answer: (B)

Retention rate measures what share of the customers present at the start of the period are still customers at the end. Here, 310 customers were there at the beginning of June. During June, 20 new customers joined, and the end-of-month total is 300. The number of the original customers who remained is the end total minus the new ones: 300 − 20 = 280. So the retention rate is 280 kept from the initial 310, which is 280 ÷ 310 ≈ 0.903, about 90%. That’s why the correct answer is 90%.