As others say 100k (presumably a file size of 100kb) is very small and is the sort of thing that might result from something like "save to web".
Assuming you can go back to source I suggest scaling up the picture to 300dpi for the finished size. The 10.2MP file will give about 75dpi straight from camera and while upscaling won't provide any more detail it will avoid jaggies. You could also print off a small piece at the desired enlargement to see whether it is going to be satisfactory.
Note others are going to descend on me like a ton (tonne ) of bricks saying they have never seen jaggies or 75dpi is fine because of the distance you will view from but is it worth the chance when you are spending £20-£30?