Why does my iPhone 4S battery die so fast?

My iPhone battery dies to fast it is at 100% charged at 7 and by like 3-3:30 it's at 10% this is rediculous my moms iPhone lasts like 3-5 days without charging it…

You must have dropped you phone multiple times of put it in water. Other than that if you left it near heavy radiation (microwave, freezer, etc) most house hold appliances could damage your battery if you leave it near them. Also turn your phone on and off a lot could cause this also. I would take it to the Genius bar near you in an Apple store to have them check it out.

Yeah this is the main Con of iPhone 4s, the short battery lifetime but they improved it in the new iPhone 5… You can't do anything about that just make sure to charge it when you are not using it

If you use it a lot then I could get that. But if you have your wifi off and you are using apps that need wifi then your iPhone will die faster and make the bill higher. And whenever you use internet, connected or not then it will drain the batery. Having the brightness on all the way will too. And you should have apps closed, if you don't know how to do that, then just double click the menu button and hold one of the apps then it will be wiggly and have a - sign and just click that.

A couple basic things to improve battery life:
Turn the brightness all the way down
Turn GPS off
Turn Bluetooth off
Turn Location Services off
Turn Notifications off

And when you're charging, let it run below 20% before you decide to charge it. Then charge it to full if you can. Don't leave it on the charger for a long time when it is at full. That will damage the battery. I hope this helps a bit

Its because of all of your applications. You can close them down when your not using them. And you can change your email settings to where it doesnt push for updates every minute.