What "special one"? You do know that 100/4= 25, don't you? If one is worth 25% then the other three must total 75%. And each one must be worth what?
No. If the last is worth 0.0625 and the others are worth four times as much, the others would be worth 4(0.0625)= 0.25, not 0.3125. And .25+ .25+ .25+ .0625 does not add up to 100%. I think you mistakenly took 1/4 of 1/4 to get 1/16 and the divided the remaining 15/16 by 3 to get 5/16 for each of the original three. You mistake was treating the first three as 1/4 each when you knew from the start that you were NOT dividing these equally.
Call the value of each of the first three "a" the last is worth "a/4". So we must have a+ a+ a+ a/4= 3a+ a/4= (12a+ a)/4= 13a/4= 1.00 so a= 4/13. each of the first tests is worth 4/13 and the last text is worth 1/4 of that, 1/13.