My applications on Google Play are free but, more as a test of how to do it than anything else, I integrated AdMob into the app. Today, after about two weeks of availability of the version that has AdMob installed, I have a report that the app has earned the princely sum of three dollars in click revenue.
This is with about 2000 total ad requests. CPM is about 1.50.
Now in France there is a thing called SMIC which is the basic minimum wage that you're paid if you have a job like licking toilets clean or, say, a nurse in a cardiac hospital. The SMIC is about 1300 euros per month so to get that level of income I would have to be making somewhere in the region of 3304 page requests per hour. I have calculated that as requests per hour over 24 hours because we all know that the ad machine never sleeps.
Sadly, I cannot live on the SMIC. I need an absolute mnimum of three times that just to maintain head above water and do all my shopping at LIDL. To keep a metaphorical wolf from Bob's door I need 10,000 page impressions per hour, 24 hours a day and a CPM of at-least 1.5.
That means I need to write about 150 apps. Better get busy! Oh, if anyone uses my app, CLICK THE BLOODY ADS!