Originally Posted by pradatta
ya actually u r right but this is not related mobile lag or hang i just want my mobile should use less ram so i m searching for that kind of answer any way u really help me with ur fast reply thanks
That doesn't makes sense. As long as your device isn't unresponsive or laggy you shouldn't bother about RAM-Usage. Android handles your available Memory quite well.
Try looking at it like this:
There isn't any use in having more and more RAM, if people on the other hand go and try to keep the RAM-usage low. As long as you don't have problems (lags or such) having free RAM is just eyecandy.
For every app killed, Android needs to load it from storage the next time, resulting in more battery drain than just letting it idle in memory