Grades and happiness

Here is my formula for happiness using the end of term grade:

2(End of term grade - 50)/10 = happiness score

Use the happiness score on the following scale:

0 - devastated
1 - very very unhappy
2 - very unhappy
3 - unhappy and considering a career change
4 - consolable
5 - trying to remain positive
6 - slightly relieved
7 - satisfied
8 - happy
9 - very very happy
10 - massive ego mixed with questioning the integrity of the course

Here is an example:

I get 85% for my end of term grade

2(85-50)/10 = 7

I would therefore be satisfied with a grade of 85%.