My iPhone automatically shuts down when the battery reaches 50%. How can I resolve it?

Question

My iPhone 4 iOS 7.0 automatically shuts down when the battery charge reaches 50%. Is it a battery problem or is it the phone?

Answer 1

Thanks, you're a life saver. Here is the report:
AC Power:
System Sleep Timer (Minutes): 10
Disk Sleep Timer (Minutes): 10
Display Sleep Timer (Minutes): 10
Automatic Restart On Power Loss: No
Wake On AC Change: No
Wake On Clamshell Open: Yes
Wake On LAN: Yes
Display Sleep Uses Dim: Yes
Battery Power:
System Sleep Timer (Minutes): 10
Disk Sleep Timer (Minutes): 180
Display Sleep Timer (Minutes): 2
Wake On AC Change: No
Wake On Clamshell Open: Yes
Display Sleep Uses Dim: Yes
Reduce Brightness: Yes
Battery Information:
Battery Installed: Yes
First low level warning: No
Full Charge Capacity (mAh): 3004
Remaining Capacity (mAh): 2994
Amperage (mA): 0
Voltage (mV): 12385
Cycle Count: 41
AC Charger Information:
Connected: Yes
Charging: No
Hardware Configuration:
UPS Installed: No