What is the relation between quality and quantity?

quality and quantity is two different thing quality - means the variety or the quality of work done.
quantity - means the amount of work done by a employee assigned to him

the relation between quality and quantity is time

Quantity refers to the amount wherein quality refers to the condition.
Quantity is often a word associated with productivity and can be easy quantifiable.
Quality has to do with the overall condition of a product or service and is not readily quantifiable so requires a more qualitative analysis.
The business dictionary defines qualitative analysis as "Examination of non-measurable data such as a firm's reputation, a brand' image, or a customer's feelings about a product." There are certainly standards of quality which have been established it really is subjective.
Read more: http://www.businessdictionary.com/definition/qualitative-analysis.html#ixzz2YrZV8zKH

the relation is when we know how to appropriate within

trade-off.....
They have a certain point/combination where they can be best.....
be it a in production or in a team.