That all depends on how well it is trained. Some 10hh ponies can jump 3 feet, while there are some 16hh horses that can't jump at all. I would say around 3'6" to 4' is what most trained 14hh ponies can jump, unless they are more athletic.
No one could give a straight answer to this. Ever horse is different, so every horse jumps a different hieght. For example, my Oldenburg can jump an average of 5-6 feet. He is my show horse. On the...
Generally they can jump about as high as their back is tall. In 1998, the highest recorded jump in the Guiness Book of World Records was 8 ft. 1 1/4 in. Check it out here...