The key here is to first estimate the number of planes that land on the runway every day. From there on we estimate the number of passengers each plane carries and approximate capacity utilisation of each aeroplane.
Let's take-off (sorry for the pun) by estimating the number of planes that land on the runway at Heathrow terminal 1. Assuming we have one landing/take-off every four minutes at the runway we get 15 planes landing every hour. Multiplying this with 24 hours in a day gets us to 360 aeroplanes a day.
Assuming, each aircraft can carry 300 passengers and @90% utilisation rate we get 270 passengers per aircraft.
Finally, we multiply these numbers - 270 passengers per aircraft * 360 (aeroplanes landing a day) = 97,200 i.e. close to 100k passengers pass through Heathrow terminal 1 every day.
We have an 88% placement rate for our 4 to 8 weeks training programs conducted in 2017/18 with students going on to secure jobs at marquee investment banks such as Goldman Sachs, Credit Suisse, Morgan Stanley, Citi Bank and Deutsche Bank among others. Please send your CV to firstname.lastname@example.org to check your eligibility for the course.