Estimation - tech

Question 1

Revenue from gmail

Answer 1

Users * ARPU

ARPU = rev from impressions + clicks + paid enterprise users

Question 2

Cost of gmail

Answer 2

#users * Cost/user
Cost/user = 
Storage cost (1cent/GB/month)
\+ transfer cost (10 cent/GB/month)
\+ computing cost (4 cent/user/month)
\+ total development cost/number of users