Is it possible to take an image that is 3543px x 4365px, (300 x 370 mm), 300dpi amd 59.0MB in size and reduce it to 1000px on shortest side and reduce the file size to no more than 100 150Kb? From what I have read it isn't. Am I wrong?
Don't worry that file size is larger than specified that it should be. Save the image as jpeg, and then have a look at it in its folder and you will see that it is, in fact the file size you wanted. Use lower resolution than 300, usually 75, but keep the 1000px shortest side. I assume that this is a spec for entering image for exhibition, and they usually want 75dpi, unless otherwise specified. They usually give very poor directions for accomplishing what they are asking for!