how many???

This is a classic case of insufficient information to solve a problem. For one thing, if you mean "build a ski resort," this could take from several dozen to several hundred people. But if you mean "build a ski," this could be done by a single person.

How big was the resort (or ski), or how much money did it cost? How long did it take to build it? This sort of information might give responders a start. But only to a point: if one man can dig a post hole in 60 seconds, does this mean that 60 men can dig a post hole in 1 second? [Ambrose Bierce]

If we treat this as a "Fermi problem," we might make such estimates as this:

Resort cost USD 100 million (or whatever). Let's guess that 70% of this is materials and 30% labor. Okay, USD 30 million in labor. If the workforce earns an average of USD 20 per hour, that would be 1.5 million man-hours. These guys are going to get lots of overtime, say 3000 hours per man-year. Now we are at 500 man-years. Suppose they did it in 5 years. Then it would take 100 laborers.

1 man with an idea and a lot of money!

How many engineers does it take to screw in a light bulb?

I think the guest means the massive indoor ski complex in Dubai called "Ski Dubai"

http://en.wikipedia.org/wiki/Ski_Dubai

You may find the information in the link above (try the corporate website mentioned, they may have the answer listed along with other details for marketing purposes). Either that or try a google search of "Dubai ski construction" (produces a lot more information).