Neither these cards nor the rulebook specifies what "a number between X and Y" means (particularly, whether or not the values are inclusive). The only source of information on this is the Gatherer ruling for Liquid Fire, which only implies that they are inclusive. Shapeshifter has no such ruling.
The rulebook should specify that players can choose X or Y when instructed to "choose a number between X and Y." In other words, it should mention that the choices include the listed values.
Also, Shapesahifter's original printed text (and the next oldest one) don't let you pick 7, but the oracle text (and the two newer printings) do. I'm just throwing that out there.