How Long Does it Take to Build a Mobile App?

This is quite possibly the worst infographic I've seen, not for the style but for the content.

Are you saying that ONE PERSON could build 1.3 777 aircraft in 18 weeks? Seriously? Or are there actually a team of 100 people building those 1.3 aircraft? So how long would it take 100 people to build an android app if they were broken into teams to do each part?

This assumes a pretty full-featured app. I'm curious on how the data was collected