3. How many times must a person see your ad before it breaks through the "clutter" and they remember it (Ad Frequency)? How many people must see it to build sales volume within your target audience? (Ad Reach) The concept is called "Effective Reach and Frequency"

http://www.visibleworld.com/blog/frequency-what-makes-it-effective/

https://audiencewatch.nielsen.com/data/help/glossary/reacheff/index.htm