I have actually harvested a nice 7 point with a deer decoy. There was a learning curve involved.
First, I tried it in the woods. Not the greatest results. Because of the lack of movement, deer had to be right on top of it before they even saw it. Sometimes they didn't see it at all. Second, if you have to carry it very far it really sucks.
Here's what worked. I set it up as a buck in a soy bean field while I tucked in to the fence row. I washed it in scent free soap prior to the hunt and added some clip on tarsal glands with scent. The decoy drew the buck in from about 125 yards and like a couple of the guys mentioned, he came in looking to fight. He had his ears pinned back and the hair across his whithers was standing up. I could have stood up and waived my arms and whistled... he was totally locked on to that decoy. He stopped boardside between me and the decoy. He then turned his head away from me and towards his plastic rival. 15 yard shot and I drilled him. The buck didn't have clue what had happened. He ran off about 10 yards, looked back, started wobbling, and fell over dead.
This is important! Try to make your set up in such a way that will force a buck to downwind the decoy (he will naturally want to anyway). Also, this was early season bowhunting and good month before the rut.
I almost fooled a big ten point with a similar set up at a different farm a couple years later. But, he didn't get as big as he was falling for the old plastic deer trick. He was about five steps from having an arrow ruin his day but, sensed something was up and did an about face.
I guess what I'm saying is try it. Your family bought you a very realistic decoy and it just might do the trick. Good hunting.