Read this short article. 

https://www.livescience.com/16493-people-planet-earth-support.html (Links to an external site.)

Evaluate their basis in coming up with the carrying capacity value and then decide whether you agree or disagree with their estimate of earth's carrying capacity for humans.

Base your opinion on your own understanding of the concept of "carrying capacity" & your understanding of human's way of life. Consider human "quality of life" or "standard of living" factor when you answer the question yourself.