iPad 3rd Generation 16gb iOS 9 with only stock application 2.3gb remains why ??

HI all I was hoping someone would be able to help me my information to you I hope this helps

IPad 3rd generation 16gb of the apps installed on the iPad the stock apps only so why does the information on the iPad say that I have only 2.3go remaining. Hope someone can help.

PPlease also see a screen shot of the iPad information