I would say all 3 are around 4'. Could be 3'9", 4', or 4'3" but all are around there. What is the name of this horse? You could look it up.. and why can't you just ask the owner the height and what shows it was at...? seems a little odd that you bought a horse and you don't know how high its been jumping.
I agree with Stilton. The first jump looks to be around 1.10m/3'6"ish. Not sure how tall the rider is, but in the middle photo looks like the jump would be hitting around chest height if she were standing on the ground, which would probably be around 1.15m/3'9"ish, *maybe* 1.20, which would make sense because they look to be 5 foot tall standards. And then in the last photo you can't see the ground, so there is really nothing to base the height on, except wild guesses.
I agree the fences are about 1.10 (3'6") - 1.20m (4'). They're certainly not 1.40 (4'6") or higher. You can easily check the horse's record online, which is probably more valuable than knowing the heights of the jumps in a couple still pictures.