A study was conducted to determine smartphone users' preferences for three popular brands: Samsung, Apple and Xiomi. A total of 570 respondents were taken randomly (170 Samsung users, 205 Apple users, 195 Xiaomi users) and asked whether they were likely to buy the same brand smartphone in the near future or switch to another brand. The survey results are shown in the following table: Repurchase samsung: 110 apple: 120 xiaomi: 135 Switch samsung: 60 apple: 85 xiaomi: 60

a. Make a hypothesis that aims to answer the problem above!

b. Use = 5% to test the hypothesis using the critical value approach