This question requires you to make an educated guess about the total annual sales of fruits and vegetables sold online in New York City (NYC). Since it's an estimation question, your interviewer will not expect an exact figure but rather want to see your logical reasoning and understanding of market trends. To tackle this, you should simplify the problem into manageable components for your estimations. Begin by considering the population of NYC and the percentage likely to purchase fruits and vegetables online. Next, you should estimate how often these purchases occur within a year and the average cost per transaction. By multiplying these estimates together, you can arrive at an estimated annual total in dollars. It's important to articulate your thought process to demonstrate your analytical skills.

An illustrative response might be: "First, let's assume that the population of New York City is roughly 8.5 million. Considering the widespread popularity of online shopping, it’s reasonable to estimate that around 30% of the city's residents may buy fruits and vegetables online, which translates to about 2.5 million individuals. If each person purchases fruits and vegetables online once a week, with an average expenditure of about $30 per transaction, we can calculate the total weekly spending. Multiplying 2.5 million people by $30 per purchase results in a weekly total of $75 million. Taking into account vacations and other instances when purchases may not occur, let's assume that people shop for 45 weeks each year. By multiplying the weekly total by 45, we arrive at an estimated annual total of approximately $3.375 billion. Therefore, my estimation for the total annual online sales of fruits and vegetables in NYC would be around $3.375 billion.

Another possible response could be: "To begin with, I estimate that the population of NYC is approximately 8.5 million. Let's assume that 40% of New Yorkers buy fruits and vegetables online, which would amount to roughly 3.4 million individuals. These consumers might make purchases on a weekly basis. Considering the high grocery prices in NYC, let's estimate that the average expense for fruits and vegetables per purchase is around $40. Thus, on a weekly basis, these online transactions would generate revenue from 3.4 million shoppers at $40 per purchase, totaling $136 million. If we account for shopping occurring about 50 weeks a year, the yearly total would be roughly $6.8 billion. As a result, my projection for the annual online sales of fruits and vegetables in NYC is approximately $6.8 billion."