Assume that there is no change in volume when ethanol and water are mixed.
Professor failure once again.
It doesn't prevent answering the question, but keep in mind that this is wrong. More so with ethanol and water, bad luck.
This problem can be found in mamy textbook. The newest one is
Darrell Ebbing, Steven D. Gammon - 2016
You tracked it down; I'm using one of his older textbooks (Ninth Addition; 2007) and it seems that it's been repeated in successive volumes. I'm a professional chemist (but, actually, not since late 2006), but, I'm going through all of my courses, because I'm contemplating taking the chemistry and physics GREs so that (I can go to graduate school; but, the last time I'm been in a classroom was in 2001 and a chemistry or physics classroom, 1999; trying to sharpen my skills back up; I took a chemistry examine for tutor.com and did awful (but, mostly because of the timing to take the examine; if there was no time limits, I would still have passed, just very rusty; but, that was a poor sign for something like heading into graduate school); just a lot of stuff lost, but, solving these problems and things are coming back, slowly but surely; but, if I ask elementary questions, which this problem proved not to be, it's because I'm trying to sharpen back up. It's very different trying to prepare for examine, if I last had a chemistry class last semester versus 22 years ago (e.g. when I started college). Since I'm just starting chapter 2, maybe you can track down a free addition of the 2016 version?