I concluded that I is a sufficient condition but why is only

I concluded that I is a sufficient condition, but why is only sufficient and not nessecary as well?

Solution

Given two conditions X and Y, there are four ways in which they might be related to each other:

X is necessary but not sufficient for Y.

Example :

X is sufficient but not necessary for Y.

Example :

X is both necessary and sufficient for Y. (or \"jointly necessary and sufficient\")

Example :

X is neither necessary nor sufficient for Y.

Example :