A top down approach will be appropriate given that we know:
- Google dominates about 80% of search.
- Google revenue in 2017 is about $100B.
- Lets assume other search services like yahoo and duck duck go capture 10% of the market.
Bings revenue = 10% * Total search market revenue
Total search market revenue = 100B/.8 = 125B
Bing's revenue = 10% * 125B = 12.5B