According to Mercers 2017 Cost of Living Survey, which city topped the list of the most expensive cities in the world for expatriate workers?

Introduction / Context:
Cost of living rankings are a favourite topic in general awareness because they help exam bodies frame questions that mix geography, economics and current affairs. Mercer publishes an annual Cost of Living Survey that ranks global cities based on how expensive they are for expatriate employees. In 2017, an African city, rather than an obvious Asian or European financial centre, topped the list, making this question especially interesting and slightly counterintuitive.

Given Data / Assumptions:
- The question refers to Mercers 2017 Cost of Living Survey.
- It asks for the city that ranked as the most expensive for expatriates.
- The options are Zurich, Luanda, Hong Kong, Tokyo and Singapore.
- We assume we are dealing with the official Mercer ranking for that specific year, not a different index.

Concept / Approach:
The approach uses both factual recall and elimination of intuitive but incorrect choices. Many learners instinctively think of global financial hubs like Zurich, Hong Kong, Tokyo or Singapore as the most expensive, which is often true in other years. However, the 2017 survey highlighted the high cost of imported goods and security in Luanda, the capital of Angola. Remembering that surprise result helps fix the answer in memory.

Step-by-Step Solution:
Step 1: Recall reading that an African city, not a typical European or Asian hub, topped the Mercer list in 2017. Step 2: Identify that city as Luanda, the capital of Angola, which is heavily dependent on imports and has high prices for expatriate lifestyles. Step 3: Compare this with Zurich, Hong Kong, Tokyo and Singapore, which are commonly in the top ten but did not hold the number one position that year. Step 4: Use this recollection to select Luanda confidently as the correct answer. Step 5: Verify mentally that no other African city among the options fits this news item, which further supports Luanda.

Verification / Alternative check:
As an alternative check, think about why Luanda would be so expensive. Factors include limited local production, high dependence on imports priced in foreign currencies, and additional costs related to security and housing for foreign workers. These conditions do not apply in the same way to the other listed cities, which, though costly, have more balanced economies. This reasoning aligns well with the reported ranking and confirms Luanda as number one in 2017.

Why Other Options Are Wrong:
Zurich is a very expensive Swiss city, but it ranked lower than Luanda in the 2017 Mercer survey.
Hong Kong often competes for the top spots but did not surpass Luanda in that particular year.
Tokyo is highly priced but has fluctuated in rankings and was not number one in 2017.
Singapore is costly for housing and transport but still did not match Luanda in overall cost for expatriates in the survey year mentioned.

Common Pitfalls:
Most students fall into the trap of picking Zurich or Hong Kong because they frequently appear in news stories about expensive cities. Another pitfall is confusing different years of the Mercer survey and transferring rankings from one year to another. Some also ignore the survey name and think of tourist experiences rather than expatriate cost structures. To avoid these issues, always link the city to the specific year and the described surprise in the article, which clearly pointed to Luanda.

Final Answer:
In Mercers 2017 Cost of Living Survey, the most expensive city for expatriates was Luanda.