What is the adult/child ratio for nursery setting?

What is the right exceed/miss ratio for goal setting?  exceeding every goal begs the question, "stretching far enough?", missing every goals is  demotivating.  In a perfect world, what is the ideal exceed/miss ratio?

• While stretch goals are an option, there is really a balance here... even using stretch goals, hitting 100% of the time can be demotivating as well if people aren't being challenged.  What's the ratio?  Most "experts" in a field, became experts through losing far more than they've won... is the school of hard knocks a requirement for long-term motivation?

• Answer:

  There isn't necessarily a number. One should set the highest goal that he or she 100% BELIEVES that he or she can achieve. It can be realistic or a stretch in other people's eyes. But the unshakable belief in him or herself and the effort to follow is the crucial factor of the realization of the goal. With the belief and effort, even as one falls short of reaching the goal, he or she will still be better off. As with the Burmese saying, "Those who aims at excellence will be above mediocrity; and those who aims at mediocrity will be far short of it."