mixing formula

So some probably will think I'm an idiot. But my baby drinks 3 oz of formula and the formula tells me 1 scoop to 2 oz of water and my mother in law tells me to just put a scoop and then half? But I feel this is wrong? What do I do? And no crap I follow the instructions but it's doesn't tell me how to mix 3 oz on the box.. just even amounts.. and this is why I got worried because I've been listening to her but this article says this.