In Kisi's Global Work-Life Balance Index 2021, Hong Kong, Singapore and Bangkok were ranked the top three cities with the most overworked populations in the world. Mr. Tan, the HR director of a multi-national computer software company, is interested to find out whether the working hours of executives in the three offices of his company are the same or not. To do so, he selected a sample of 8 executives from their Hong Kong, Singapore and Bangkok offices, and collected the number of hours worked per week in Table 3-1.

Table 3-1: Weekly working hours in three offices