And here’s the answer for the bonus: If the man had already put sugar in his coffee, it would still taste sweet. If the waitress really replaced the cup, the fresh coffee shouldn’t be sweet.
Are you ready for the answer?
It’s not complicated. Just take a close look at the picture. The answer is 5… and that’s it. All the other cups wouldn’t get anything because the tubes leading to them are blocked off at some point. You see, even though the riddle asked for the cups in order, that didn’t mean more than one cup was going to get anything.