With all due respect to my colleagues, I'm going to try to clarify the other answers here. As they've rightly identified, you're experiencing simple anatomy -- the muscles that move those two fingers are joined.
However, seeing as this is human anatomy, you should not try to fight it. In my opinion, performing the above exercises as described, especially as a beginner, will lead to tension, which is something pianists should avoid at all costs.
Tension is caused when muscles are fighting against one another -- pulling in opposite directions. Doing the exercises above without a proper understanding will simply exacerbate this. They can definitely be a help, but the way they are worded and described above may lead to some erroneous ideas which I address below.
That being said, your problem CAN be solved -- however, in my opinion it's not a matter of finger independence, but instead a matter of position and attack.
By position, I mean that you should rest your hands on the keys so that the fingers are relaxed and naturally curled downward, pointing at the keys.
Here's a crucial point on attack: whenever a finger is not currently depressing a key, it should be comfortably relaxed. The exercises above, though not entirely wrong, may lead to the erroneous idea that when you play with your pinky, you must force your ring finger to stay up. This is not correct.
Instead, when you play with your pinky, your ring finger should be completely relaxed. So if you do the exercises above, don't try to force the other fingers not to move -- instead, focus on simply moving that one finger and completely relaxing the others. It's OK if they move together -- as long as the other is relaxed, it should not move with enough force to depress an extra key.
Also, pressing the keys should not be a fingers-only action. The above exercises also may lead to the erroneous concept that you need to "freeze" your hand and only move the finger muscles. This is also false. Allow the wrist and hand to have full range of motion when playing, but simply extend the fingers being used and relax the others.
I could go on, but hopefully this is a help.