I've been provided an excel deliverable that includes xy coordinates. There's no reference to the coord/projection used to generate those xy's. I've provided a sample of the points. I'd be curious to know the process others use to plot a set of given points without knowing the coord/projection being used.
First things first, work off copies of the original deliverable so you always have that to fall back to. They don't appear to be geographic coordinates so you can cross those options off the list. Are you in the US? You have two likely options then- UTM or State Plane. Figure out which relevant UTM/State Plane Zones address the area you know the data is supposed to be located in and then attempt to apply those projection definitions to the data. It's gonna be trial and error but these would be your best educated guesses to start with.
