In theory, if one is occupied, then you can add whatever size you want. But better add 8GB of the same memory to ensure stability (I.e. Not all RAM sticks like to work with each other) and dual channel operation
Is this new or refurbished?
With 8GB RAM installed, is it occupying one of two slots? If one slot is occupied, and upgrade is desired, can one add 4GB, 16GB or must it be another 8GB RAM module?
Dont think this is a deal. Refurb one can be bought from dell outlet with 1 year warranty for £300-£350. altho called refurb,they are just like brand new
Think I prefer the HP https://www.hotukdeals.com/deals/14-hp-laptop-i5-8250u-4gb-ram-256gb-ssd-full-hd-449-now-with-50-cashback-ao-3-colours-to-choose-from-free-mcafee-internet-security-more-in-op-2941160