Just for running office you don't need more than 8GB RAM.  Adding more RAM increases multitasking capability of a computer, it doesn't make computer faster.  Get a Solid state drive (SSD) which will make this machine faster. Please make a note that you either have to clone the SSD or do a fresh start by reinstalling the operating system.    A compatible SSD for your machine. Please find the link here.    Here's a video of SSD installation process.  [URL]  
I am wanting to upgrade the RAM on this laptop to make it faster.  I have already done all of the Dell updates for firmware and BIOS, it did help some but still is too slow.    It says I already have 8GB of RAM.  I would like to add 8more. I am attaching a screenshot of system info.  Thanks for your help!   [IMAGE]
Dell Inspiron 15-3567-RAM upgrade